After much testing on my PII 450 with ~380 megs of RAM, I've found that MAME .78 works best. Smooth sound, even with overlays. The bezel artwork does slow things down a bit, tho, on some games (Asteroids is a good example). No need to frame skip, etc. Also running an authentic SoundBlaster card and Win98' with all drivers updated, etc. Using MAME32 but any .78 MAME should yield similar results.
So, if you're looking to play just the classics, that seems to be the best version to do it with, IMHO.
BTW, this is also the first version in which ARMOR ATTACK is fully playable with sound, overlays, etc.
Maybe this will help someone, somewhere, someday!
