can somebody explain the difference in the duron/athlon/athlon xp.....besides the price? is duron crappy or something? ive never used amd and im probably going to get one for my new cab pc. is there anything i need to know before buying amd?
An Athlon is like a Pentium III. It's pretty old, but definitely good enough for MAME. You might run into issues if you wanted to play some decent PC based games though.
Athlon XPs are like Pentium 4s. Aside from the spankin' new Hammer 64 bit processors, they're the latest and greatest. A high megahertz version of this CPU class will run pretty much every PC game out there.
Durons are AMD's answer to the Intel Celeron. I very highly recommend against going with either the Duron or the Celeron processor. They are the slimmed down versions of thier higher end counterparts (P4 and AthlonXP), and technology seems to run over them pretty quickly, meaning, all your applications will start getting slow slow slow a lot sooner then they would if you had an AthlonXP. Whether that matters as much in your arcade cabinet, well, that's your opinion. Personally, I'd spend the extra loot and get myself a real CPU

Technically, Durons have 1/4th the amount of L2 cache as the AthlonXP, but also run a lot cooler (if that's an issue for you).
Generally speaking, AMDs offer a better price over Intels, but tend to run hotter and have higher PSU (Power supply unit) requirements. In the marketplace, AMDs are sort of the Linux to Intel's Microsoft (they're the underdog). So if you're into that evangelistic kind of thing, that's another reason to go with AMD

HTH.
/Steve