I just got my Quad set up today and used a small application from Tom's Hardware to assign affinity to specific applications. There are many other ways to do it. Setting the affinity in config.wtf didn't end up working for me, so I just went this route until I can figure out why

You can find the article and application here: http://www.tomshardware.com/2004/05/...uck/index.html

I created a new application profile for WoW.exe and set the affinity to all 4 cores. With that setting, all cores have a balanced load when all 5 instances of WoW are running.

Hope that helps.

-Goose