This is a list describing different Windows versions in terms of game compatibility.
Windows 98: Best all-in-one operating system for vintage gaming computers. Basically a much more refined continuation of Windows 95. Good DOS compatibility either by DOS window or rebooting into DOS. Emulates USB mouses and gamepads in DOS window as well. Has numerous features that Win95 got only with the OSR releases and which weren't present in its original release, such as support for P6 (Pentium Pro and up), FAT32, selection of IRQs, AGP, UDMA, USB and MMX. Furthermore, SSE and multiple monitor support is exclusive for Windows 98 and up. 3rd party USB mass storage drivers are only available for Windows 98 SE due to its newer USB stack, so this revision is by far preferable. Up to 512 MB RAM without tweaking, with tweaking up to 1 GB.
Windows XP: Last OS from Microsoft so far to support Gameports, the IPX protocol, MIDI device selection and EAX 3D sound hardware acceleration. Relatively good Win9x game compatibility. DOS only via NTVDM emulation, has basic Sound Blaster support (SFX part only).