Before you go hog-wild, know that WoW runs graphics off the CPU, not the GPU.
I bench-tested the CPU (AMD Athalon DuoCore X64 4600+) and GPU (GeForce 8800DTS) and was surprised to discover my GPU loping along while the CPU was dying at 75%. When it hit 100%, it started tossing in dead clock ticks and disconnects me from WoW.
Yes, removing addons will delay the ultimate collapse, but who wants to play at 6fps? I'm investing in a mid-level i7 and motherboard (Gigabyte or Asus, haven't decided yet).
(You can remove the driver from your hardware manager, advanced tab.)
Check out "Best Gaming CPUs" [ http://www.tomshardware.com/reviews/best-gaming-cpu,2599-7.html
] for some good intel.