vc++ 2005 switch for compatibility with vc++ 2003

Hi,
i am a newbie in both C++ and the Visual Studio world.
I try to use some headers and static libs, that i suspect they were made with vc++ 2003 and now throw errors and warnings when i try to use them with vc++ 2005.
Is there a switch, that can make them compatible?

Thanks

No, 2005 incorporates breaking changes in the compiler that will break existing code that does no adhere to the C++ standard.
Perhaps post these errors/warnings and some sample code and we can help you fix it.