I made the switch from 178.24 to 180.48 and also updated my nforce drivers to 15.23 and my performance went down by quite a bit in eve (multi clients) and eq2. I am running a 9800GTX.
Also, closing down the extra game clients would not always bring the performance back up to where it was when i had only the 1 client going.
This is with a fresh vista 64 install. I will be going back to 178 and the 15.01 nforce drivers.