Ok I have this code...

Code:
#include <windows.h>
#include <stdio.h>
#include <conio.h>


// prototypes
BOOL FullScreenConsole9x(void);
BOOL FullScreenConsoleNT(void);

// ---------------------------------------------------------------------------
BOOL FullScreenConsole9x(void)
{
    BOOL ok = FALSE;

	// console finding guid
	// a unique number to identify this console - replace this with your own
	#define CON_GUID TEXT("CON_GUID-{68E311EF-BF32-4b0f-8D35-E84E4A463096}")

	// hwnd for console window
	HWND hConWnd = NULL;

    // magic command
    WPARAM magic = 57359;

	// buffer for storing a substitute title
	TCHAR szTempTitle[] = CON_GUID;

	// buffer for storing current console title
	TCHAR szTempString[MAX_PATH];

	// obtain the current console title
	if( GetConsoleTitle(szTempString, sizeof(szTempString)/sizeof(TCHAR) ) )
	{
		// replace the current title with substitute title
		SetConsoleTitle(szTempTitle);

		// give it a chance to set in
		Sleep(50);

		// locate the console window

		// console window class on W9x is "tty"
		hConWnd = FindWindow(TEXT("tty"), szTempTitle);

		// restore the original console title
		SetConsoleTitle(szTempString);

	}

	// verify the console hwnd
	if ( hConWnd != NULL ) {

	    // pause before changing to fullscreen
    	Sleep(450);

        // this method works by faking a keyboard command
        SendMessage(hConWnd,WM_COMMAND,magic,0);

        ok = TRUE;

	}

    return ok;

}

// ---------------------------------------------------------------------------
BOOL FullScreenConsoleNT(void)
{
    // typedef function pointer for undocumented API
    typedef BOOL WINAPI (*SetConsoleDisplayModeT)(HANDLE,DWORD,DWORD*);

    // declare one such function pointer
    SetConsoleDisplayModeT SetConsoleDisplayMode;

	// load kernel32.dll
	HINSTANCE hLib = LoadLibrary("KERNEL32.DLL");
    if ( hLib == NULL ) {
        // highly unlikely but good practice just the same
        return FALSE;
    }

	// assign procedure address to function pointer
	SetConsoleDisplayMode = ( SetConsoleDisplayModeT )
		GetProcAddress(hLib,"SetConsoleDisplayMode");

	// check if the function pointer is valid
    // since the function is undocumented
	if ( SetConsoleDisplayMode == NULL ) {
        // play nice with windows
	    FreeLibrary(hLib);
		return FALSE;
	}

	DWORD newmode = 1;	// fullscreen mode
	DWORD oldmode;

	// get handle to stdout
	HANDLE hStdOut = GetStdHandle(STD_OUTPUT_HANDLE);

	// pause before changing to fullscreen
	Sleep(500);

	// set full screen mode
	SetConsoleDisplayMode(hStdOut,newmode,&oldmode);

    // play nice with windows
	FreeLibrary(hLib);

    return TRUE;

}

// ---------------------------------------------------------------------------
int main(void)
{

    OSVERSIONINFO VerInfo;
    ZeroMemory(&VerInfo,sizeof(VerInfo));
    VerInfo.dwOSVersionInfoSize = sizeof(VerInfo);
    GetVersionEx(&VerInfo);

	// Why a switch? because I felt like switching... har har
    switch ( VerInfo.dwPlatformId ) {

		case VER_PLATFORM_WIN32_NT :
        	FullScreenConsoleNT();
			break;

		case VER_PLATFORM_WIN32_WINDOWS	:
        	FullScreenConsole9x();
			break;

		default:
			break;

    }

	// issue a report
	printf("This is a test.\nHit enter to exit");

	// wait for keyboard hit
	getch();

    return 0;

}
I found on a Here. Now, when I try to compile the code in VC++6 I get errors, but when I compile in Dev-c++ it works perfectly, any ideas why?

Here are the errors for VC++6:
--------------------Configuration: fullscreenconsole - Win32 Debug--------------------
Compiling...
fullscreenconsole.c
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(71) : error C2059: syntax error : '('
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(74) : error C2065: 'SetConsoleDisplayModeT' : undeclared identifier
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(74) : error C2146: syntax error : missing ';' before identifier 'SetConsoleDisplayMode'
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(74) : error C2065: 'SetConsoleDisplayMode' : undeclared identifier
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(77) : error C2275: 'HINSTANCE' : illegal use of this type as an expression
c:\program files\microsoft visual studio\vc98\include\windef.h(252) : see declaration of 'HINSTANCE'
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(77) : error C2146: syntax error : missing ';' before identifier 'hLib'
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(77) : error C2065: 'hLib' : undeclared identifier
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(77) : warning C4047: '=' : 'int ' differs in levels of indirection from 'struct HINSTANCE__ *'
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(78) : warning C4047: '==' : 'int ' differs in levels of indirection from 'void *'
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(85) : error C2146: syntax error : missing ';' before identifier 'GetProcAddress'
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(85) : warning C4047: 'function' : 'struct HINSTANCE__ *' differs in levels of indirection from 'int '
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(85) : warning C4024: 'GetProcAddress' : different types for formal and actual parameter 1
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(89) : warning C4047: '==' : 'int ' differs in levels of indirection from 'void *'
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(91) : warning C4047: 'function' : 'struct HINSTANCE__ *' differs in levels of indirection from 'int '
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(91) : warning C4024: 'FreeLibrary' : different types for formal and actual parameter 1
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(95) : error C2275: 'DWORD' : illegal use of this type as an expression
c:\program files\microsoft visual studio\vc98\include\windef.h(141) : see declaration of 'DWORD'
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(95) : error C2146: syntax error : missing ';' before identifier 'newmode'
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(95) : error C2065: 'newmode' : undeclared identifier
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(96) : error C2275: 'DWORD' : illegal use of this type as an expression
c:\program files\microsoft visual studio\vc98\include\windef.h(141) : see declaration of 'DWORD'
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(96) : error C2146: syntax error : missing ';' before identifier 'oldmode'
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(96) : error C2065: 'oldmode' : undeclared identifier
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(99) : error C2275: 'HANDLE' : illegal use of this type as an expression
c:\program files\microsoft visual studio\vc98\include\winnt.h(207) : see declaration of 'HANDLE'
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(99) : error C2146: syntax error : missing ';' before identifier 'hStdOut'
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(99) : error C2065: 'hStdOut' : undeclared identifier
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(99) : warning C4047: '=' : 'int ' differs in levels of indirection from 'void *'
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(105 ) : error C2063: 'SetConsoleDisplayMode' : not a function
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(108 ) : warning C4047: 'function' : 'struct HINSTANCE__ *' differs in levels of indirection from 'int '
c:\documents and settings\rcapote\local settings\temp\rar$dr03.922\fullscreenconsole.c(108 ) : warning C4024: 'FreeLibrary' : different types for formal and actual parameter 1
Error executing cl.exe.

fullscreenconsole.exe - 18 error(s), 10 warning(s)