Definitely upgrade your ram to 1gb at the least asap. Eq sessions use about 600 or so mb of ram each so 512 is not even enough to run one session, it will begin to go to virtual memory (your hard drive) so that will slow you down to begin with. When you say you got a dual processor do you mean like an athlon 64 x2? If so there are some articles you might want to read. I'm copying this from the eqforums as I've seen it a myriad of places but this should work:
Updated drivers for your video card will NOT correct this issue.
AMD Dual-Core Optimizer - The AMD Dual-Core Optimizer can help improve some PC gaming video performance by compensating for those applications that bypass the Windows API for timing by directly using the RDTSC (Read Time Stamp Counter) instruction. Applications that rely on RDTSC do not benefit from the logic in the operating system to properly account for the affect of power management mechanisms on the rate at which a processor core's Time Stamp Counter (TSC) is incremented. The AMD Dual-Core Optimizer helps to correct the resulting video performance effects or other incorrect timing effects that these applications may experience on dual-core processor systems, by periodically adjusting the core time-stamp-counters, so that they are synchronized.
Guess what - EQ is very likely using the RDTSC machine instruction, and thus runs into a problem when the RDTSC instruction retrieves an unexpected value. In my case, this was inevitable for any game play period lasting longer than 10 minutes.
This situation results in a "gliding" character model that slides across the ground with only a very occasional (notably infrequent) "walk" animation, animated torch flames that start at position 1 (low) and leap to position 8 (high poof) without transitioning through the sequential 2-7 animations (personally seen in blightfire on tiki torches near the gnolls), mob animations that "warp" erraticly on screen, and spell graphics which are "jerky" and go from no display to final-animation frame. Installing this optimizer utility fixed this issue for me without causing additional problems. I would strongly advise that you study the documentation carefully before implementing this fix for your particular case, but it may be exactly what you're after.
Information on the optimizer is available from:
http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_871,00.html
Information on the issue for programmers is:
http://support.microsoft.com/kb/909944/en-us
I was most relieved to find such an easy fix existed. Hope this helps you, and any others suffering from this issue. Good luck!
(PS: Devs, you might want to see about fixing the use of RDTSC, if it applies as I think it does.)
eqisdead