In case you haven't heard of it, there's a cheat built into galaga supposedly by one of the original programmers so that he could get the high score on any machine... Well, it's true.
Download the attached file "galagao-1.txt" convert the extension to ".sta" and then place the file in "program files/mame/sta" unless you installed mame to a different place, then it's up to you to find where to put the file.
Once you've done that, start "galagao" aka. "Galaga (Namco)", but NOT "galaga" aka. "Galaga (Namco Rev. B)
When it's ready for coins press F7 then the #1 (the same one you use to start a game, not on the num-pad.
If you did all that right, it should load up to just after the bugs have stopped shooting. And again for those who don't know, for the rest of the game, not a single other bug will shoot at you!
Have fun!
[edit] for some reason it's not working for me any more... sorry for wasting your time if it doesn't work for you either.[/edit]