Well, two of these bad boys:
Newegg.com - Intel Xeon E5430 Harpertown 2.66GHz 12MB L2 Cache LGA 771 80W Quad-Core Processor - Retail
Would do wonders. I bet they can go up to 4GHz with ease... if they have adequate cooling.
Anyhoo, I just ordered a Yorkfield... and hopefully, the thing will arrive tomorrow! Will tell you what happens.
And yeah, this time, it's another Xeon processor.