Also... saying "I want to run mame" is a litle vague. If you want to say, run pacman then dos is fine, but if you want to run killer instinct or mortal kombat then the hardware requirements are so great that you might as well run windows. Also I wouldn't reccomend 98, mostly because none of the developers run 98 as their test machine anymore and utilities, front-ends, and emulators are no longer guaranteed to run (or run well) with lesser versions of windows. As a matter of fact, newer emulators (chankast) won't run in anything other than xp. Xp is really the way to go if you intend on adding on int he future. As for those dos games, well that is what dosbox (the pc dos emulator) is for.

There is no need to cripple your whole setup over those games.