WoW is different beast altogether, with many factors determining overall performance.

Network (internet) speed, CPU, O/S and drivers etc...

Why are u running 64bit Vista instead of 32bit? Also, the core2duo is lots lots better cpu, and the Vista 32bit is well rounded.

Do you have the correct 64bit drivers for your sound and video cards? Also, the increase in your resolution (even 1 step above) is a big hit on the Graphics card load, needing an extra 100mb of memory or so. Try lowering the spec down to 1152x864