Need more info on the laptop in question. If it's an older one, you're not likely to be happy with anything past Win95, particularly if you use it for games that use DirectX. (Video driver problems, and lack of dedicated RAM for the video cause all kinds of mouse/keyboard lockups.)
I've run Win98SE on an older high-end Hitachi (64Mb RAM) without too many problems, but I cannot run any games past AOE - Rise of Rome without having the machine lock up the mouse continually. Microsoft says that it's an issue with insufficient RAM to support both the machine and the video under DirectX, and says to install more RAM (yeah, right, on an older, proprietary system...).
As already noted, Win2K will also require a lot of RAM, so that may not be a good idea either.
Lady Niniane