i've played WoW and Everquest for years and years, i know all about raids and how frustrating it can be with 70+ people running around.
Most poeple dont understand untill they spend 12-14hrs a day raiding in a high-end guild, that even with a beefy system, an old game like Everquest can REALLY slow down your computer.
your system is not bad, but you may be right about the CPU.
if you have an AM2+ board, get a phenom
if you have an AM2 board, get an x2 6000+ BE (the 65nm brisbane version, not the 95)
if you have a skt 939 board, you'll need a complete overhaul (but your video card is plenty for now)
im more of an everquest fan than a wow fan, but those raids are seriously going to tax your system.
(you'll want to get that 10-15fps in raids, up to 30-35 at LEAST)
its hard to worry about your healers, tanks, DPS, and support teams while your jumping around due to poor framerate.