XP is the program formerly known as Whistler (an attempt to meld the Consumer - or Win9x - and Professional - NT Kernal - flavors of Windows into one, single OS). Win2K is good unless you have legacy peripherals (my modem and sound card are not supported!) W95Sr2 was really good - better, even than Win98, but Win98SE and Win2K are the only "good" OSSes that MS has on the market right now, IMO. Well, aside from DOS, that is... ;-)