The ram is very dependant on the mobo you pick. Many will tell you that BH5 chips like OCZ VX or Musckin redline are the best because it can hold very low timings at high speeds, but unless you use a DDR booster or volt mod your board the DFI ultra series is the only board that can give it enough juice 3.2v+, and even then you need active cooling on the ram.
For any other board good TCCD chips or TCC5 chips with 2-2-2 timings will be the best, but about twice the price of value ram. The real truth is highspeed low latency ram only really benifits synthetic benchmarks on A64's, and doesn't help realworld performance hardly at all because A64's aren't starved for bandwidth. Unless benchmarking is your main objective, I would recommend saving money and going with value ram and spend your money on a better videocard or power supply
*edit*
Or use the extra money to get 2gb of ram, I hear some of the new games like BF2 will benifiet from more ram