Well, I decided to buy the Radeon 8500LE:
http://www.directron.com/directron/ati8500.htmlI called Directron and they said it was an actual OEM card built by ATI. It was 72 dollars, but I'm going to try to pricematch it with buyxtremegear.com which has it for 60.00. If you want 10.00 off the price, add CES2003 for a $10.00 discount! So, if I can get the pricematch (they actually don't pricematch, they meet halfway), I'll have bought this card for 56.00 plus shipping.
However, I saw a black Enermax case with rainbow LED lights that was very cool. Now, I've already bought a case but I now plan to use the computer I'm building as a new main computer and buy spare parts on the side for the Mame computer.

So, the hunt starts again! This time, since I don't have to support Windows XP, the Sims, or anything else BUT mame, I have to find a new motherboard/CPU/memory, video card, sound card, and hard drive. I hope to keep this under $300.00! Wish me luck!
Again, thanks to ALL who responded! This message board is actually very active and helpful!

Edit on January 23: I received the card from Directron. It's actually a Sapphire ATI. Doh! I called and was told that whoever I spoke to Monday must have misunderstood. However, since I essentially received $26.00 off of this card ($48.00 8500LE!! - 10 coupon, 10 new customer, 6 pricematch), I'm going to stick with it. Besides, the Mame machine will actually have to use a built by ATI card, but my new computer won't....