We say most because WinXP, like Windows 2000, runs off a 32-bit kernel -- doing
away with the 16-bit DOS layer that Windows 95 and 98 ran off of. This creates
some problems for older games that are expecting a straight DOS environment.
Just like in Windows 2000, one must run DOS through a window within the
Windows XP environment -- effectively emulating DOS. This makes configuring
memory settings as easy as opening up the window properties and tweaking
things, which is important because many older DOS-based titles have strange
memory requirements. The one thing that gave us recurring issues was getting the
sound hardware properly configured for these older games. Even though most
current sound cards can handle emulating the older sound blaster compatible
defaults, the games simply cannot detect the cards correctly (most likely the DOS
emulation is the culprit here). Bottom line is if you still play old school titles that
require DOS, you're probably best off running a dual boot of WinXP and 98 -- that
way you can force Win98 to load up DOS for you.
-http://www.gamespy.com/hardware/september01/winxpgaming/index2.shtm