M8 Im very into this Mame & TV lark! I started out with a matrox G400max with its dual vga sockets. It can be bios flashed in such a way that it will always output to shvs/composite as the main display (even in dos! dont need drivers) perfect for a mame/emulator box etc....
Ive had these cards in the past:
G200 Marvel (has built in mpeg hardware capture & breakout box)
these matrox cards are great
But recently i wanted some more power so i bought a cheap Geforce 4 M440 with tv-out. It works better than i thought it would as the thing drives two displays at once, tv & monitor!
it works great
no faffing around just plug the required leads in and off you go!