AM2 Memory

I'm about to build myself a new HTPC and I plan to order an AM2 Proc and Mobo and MCE 2005. I'm looking at getting the A64 3000+ or the A64 3200+. Since I'm using hardware encoders I don't need that much processing power and I was wondering if I should go with 1Gig of DDR2-667 or the more expensive DDR2-800. I know the memory times can get a little funky and I would like to know which combination of memory and proc would be most effective. I will not be overclocking this project so that isn't even a concern but I would like to get the most efficient combination from a processing perspective. Would one of the Sempron chips be better? Any insight on this subject would be greatly appreciated.

Thanks!