My performance in dalaran is absolutely horrible, so maybe it's time to upgrade, here's my current specs:

nforce 680i mobo (don't know exact brand/type)
4 GB RAM
E6700
8800 GTX

main is on a 27 " lcd TV (1366*768), clones are on a 22" screen(1680*1050 divided in 4 regions)
graphics are already turned down to a minimum for the clones and run at 5 fps
main is also turned down a bit (viewing distance, shadows, AA, ...)

in dalaran i get really bad fps, sometimes as low as 3-4. At times it's so bad that the main wow just crashes...

What should i upgrade to get good performance? 5 fps on slaves doesn't bother me at all, but i would really like to run the main with everything turned on, and maybe even on a 50" plasma (1920*1080).

What's the bottleneck in my pc? RAM usage is usually 80-90%, but cpu usage is close to 100% on both cores at times.