You didn't mention HD space either, perhaps texture chache is stored there and you are out of space? The only other problem I can think of is that WinEQ has some conflicts with EQ since they changed the mouse cursor. Try loading both accounts without WinEQ (but you may wish to create a second EQ file to reduce lag).
On highest graphics settings your AMD 3.3k 1536 ram 128 radeon computer should have no problems unless you have a crappy little 10 Gb Hard drive...
One of my systems; P4 HT 512 Ram 40Gb Hd and a 128 radeon. This one can handle 2 boxing EQ on one computer without using WinEQ or a secondary directory. Second account suffers lag when minimized, but that's just a directory issue. I always have high / full graphics and sound turned *on*.