I like Win98SE, but there is no point in putting it on new hardware, plus its no longer supported by MS for critical patches. Its best to match OS with Hardware of its time and game of its time, less likely to have problems.
Like I have a Pentium 1 MMX, 200 Mhz running dual boot Windows 95B/98SE for older gaming like StarCraft, Diablo 1, WarCraft II, and the stack of Sierra Games that require older hardware for sound support on the Sound Blaster 16 ISA Card. The 3 games listed actually run fine on newer hardware as long as it is a 32-bit OS, but I've heard about gaming troubles with 64-bit OS.
Ever since Windows 2000 Pro, I have switched over to NT OS for security and reliability. Stinks though that MS will be canning support on Windows 2000 Pro/Sever in January 2007 from what a friend told me.