Gongo, if you're going to keep the RAM at DDR400, there's only one way to go, IMHO, and that's with Corsair TWINX1024-3200XLPRO.
I nicknamed them "Wallet Busters" a few posts back :D, because they run 315.00 a pair at newegg, but they have 2-2-2-5 timings @ DDR400 and gave me an instant 15-20%...