The general consensus is still 2x1GB. 4X512MB puts a bit more stress on the memory controller, while 1x2GB does not allow for dual channel, and 2GB sticks are rare (only a couple of G.Skills), and have pretty loose timings (6-6-6-18 for DDR2 800). Finally, 2x1GB allows for future upgrade to 4GB if you ever feel the need (although then you'll get the extra load on the memory controller).
Look for some good DDR2 800 RAM (or faster
) with Micron D9 chips.
Since you have an Intel rig, timings are not *that* important. Tighter timings will indeed give slightly better performance, but if you can achieve higher speeds with looser timings, it'll be better! Intels love bandwidth
Look for some good DDR2 800 RAM (or faster

Since you have an Intel rig, timings are not *that* important. Tighter timings will indeed give slightly better performance, but if you can achieve higher speeds with looser timings, it'll be better! Intels love bandwidth
