Okay, so I've gotten my 5-boxing already set up on two computers.

The 4 shammies are comfortably settled into the quadcore box with 4gigs of ram,
but my pally tank is still on my old Pentium 4, which is showing its age in Northrend (it's stll got an AGP slot for cryin' out loud).

So as I'm seriously planning to resume my 5-boxing thanks to news of patch 3.2,
I'd like to upgrade my old computer considering it's where I'm looking most of the time.

My question is, would upgrading the CPU alone be sufficient to run WoW at the "ultra" graphics setting in Wrath?
Or should I get a new motherboard, ram, and graphics card as well?

My current computer has:
- Pentium 4 3.0GHz (2 cpus)
- 2gigs of ram (i think 400's)
- Radeon X1950 Pro