btw, dont run mame32 if you are worried about speed.
Thats your first speed up there...
Go command line if possible. of course with those old versions, the command line is DOS... but thats ok... you shouldn't be using winNT or XP on that system anyway. 98 runs the dos version just fine. You might have a sound card issue... but you will probably be fine.
Also, look at non-mame emulators wherever possible. Almost every other one is MUCH faster then mame.