best choice on MB/CPU?

[Levangles]

hey guys/gals....

as much as i'd love to hop into some of these new FPS games i'm afraid my poor little cupoooter is running out of steam. So, i guess i might as well spend a couple hundred bones and get a new mb and CPU. My other items seem to be alright i think. But i really would like to know what you guys think would be suitable for me to get in terms of getting some fps games to run smoothly.

currently running an athlon 2800, 1g ddr (any way to check this forsure?, not possitive on ddr), 5500 256mb nvidia card, 120gig hd and whatnot...

just wondering whether athlon/intel is superior for gaming purposes and if there's anything else i should consider changing/upgrading. think i have a 420 power supply, and my case seems somwhat decent

any tidbits of advice (preferably in lamans terms if possible) would be great, particularily in terms of brand/model of MB or CPU brand/speed

thanks in advance