It has dual 400fsb mem channels. So you could get 2 512 ddrs or even 2 1gig sticks of ddr if you wanted. I recommend PC3200.
As for CPU its all about how much you are trying to spend. I found the 3000+ to be the most reasonable price for me. (I found it for 125$) Just make sure its Barton. If you have enough money for the 400 fsb rather than 333 than go for it.
www.newegg.com great prices and great shipping, I highly recommend