You mentioned all your computer stats except for your hard drive. What kinda storage are you using? I ask because on one of my secondary systems I was having real problems - hearthing to Dalaran meant a 30 minute walk from the horde inn to the fp, I was getting about 1 frame every 30 seconds. Then I sat down and thought to myself "I know this is because Dalaran is FULL of little doodads and textures" and determined that my chokepoint was the 5400rpm IDE drive I was running in that system. I looked in my closet and found the 10k SATA Raptor I hadn't found the time to install, plugged it in, copied my WoW directory over, set up symlinks, and fired it up.

Just like that, the system was smooth as butter with two clients getting 15fps steady in Dalaran.