As I am considering the possibility of 10-boxing and I have to build a new machine anyhow...
It seems like it would be possible to run 8 instances of WoW on a quad-core box with 8GB RAM and either a top end video card or dual video cards (not SLI) and get decent performance. Maybe a Q9450 and a single or pair of 8800GT's, to run 8 accounts at minimal settings (800x600, max performance settings) would do it.
My backup machine will run 2 instances no problem so voila I'd be at 10 right there.

It's too bad the test realm is down right now or it would be easily possible to test - just log 4 accounts in to the normal realms and then again to the test realms!

Is anyone running a Q9450 that would be willing to try pinning 4 instances to 2 cores and tell me how the performance is?