I'm recently converted to Win7. I run one GFX card and two LCDs.

Previously on WinXP I had noticeable lag on both WOW Windows when one was on the 2nd LCD. On Win7 there's no lag.

WOW itself (even solo-boxing), I had to turn down some of the settings a teency bit to get the same framerates, I also noticed that oddly enough, I had to first login to a toon in Dalaran or another major city before my 'twins' out in the boonies would get decent framerates?!?