Not a bad set-up there, ive got a San Diego, its a good chip, OC'd it benches in the FX range according to Sandra. i wouldnt have gone for ATi personally. Make sure when you OC, even if you only OC to like 2.5 or something and see others can do 2.9, best to keep it in a 1:1 ratio with your RAM, running Async mode ive found doesnt bear as good results, i actually was getting ever so slight intermittent lag on NFSMW at 2.7, RAM divider was DDR333, but running at a lower OC of 2.53 allows me to do a 1:1 Sync OC - no longer any lag and it runs noticeably faster in windows as async was making it sluggish, im running nForce4 too:S, see how you go though
best of luck, tell me what you get, its different with each individual chip i know but mine was unstable at a Vcore of 1.575v and even sporadically at 1.55v, some can comfortably do these levels.
