You'll want the fastest RAM possible, as the FSB limits dont seem to be better with the 45nm chips over current Quads.
When are you expecting the chip? If its not till January, my advice would be to wait as long as possible to buy RAM and see what DDR3 prices are like. At the moment, decent DDR3 is around £200-£250 for 2GB depending on where ya go
I reckon we've seen all we're gonna see from DDR2, and most enthusiast kits will do 600MHz+ at 5-5-5 (or 4-4-4 with more juice)