Again, I am also 5-Boxing with ISBoxer on a single PC.

i7-2600k (4.4ghz on AIR - 65c at 99% load)
Asus P8P67 Intel P67
Corsair Vengeance 12GB (3x4GB) DDR3 PC3-12800C9 1600MHz Triple Channel Kit
Sapphire ATI Radeon HD 5850 Extreme 1024MB GDDR5 PCI-Express Graphics Card
2x 1.5TB drives (soon to be 1x1.5TB and 1x1.5TB RAID0) (One for Windows and other applications, one exclusively for WoW/Premier/Photoshop etc)
Windows 7 Ultimate 64 Bit

Good settings on the alts, high settings on the main. Limited myself to 60 fps in ISboxer and rarely fall below 50 fps.