Quake 4 looks like Doom 3 in a lot of ways, and it seems to bear similar performance attributes, too. The game is chalk full of visual detail. However, it still manages to push today's processors at 1024x768. Where CPU scaling is really apparent, AMD holds an undisputed advantage. That's not to say Intel is far behind, but the Athlon 64 FXs genuinely trounce the Extreme Editions. The dual-core X2s smoke the Pentium Ds. And the mainstream Athlon 64s best Intel's Pentium 4, though by a slimmer margin

It'd certainly be nice if adding an extra gigabyte of memory helped boost the scores. Unfortunately, memory capacity doesn't seem to be a limiting factor, even in light of the Ultra Quality setting's extraneous texture usage. Gamers currently running just one gig should get perfectly reasonable performance.

Instead of buying memory, think about a second graphics card for SLI operation. The technology doesn't make much of an impact at 1024x768, but as you start switching on eye candy features and ratcheting up the resolution, the extra power kicks in and catapults frame rates.