Grats on your upgrade.
It's also important to note that EQ2 is a resource intensive monster.
I started playing in the original beta with a P4 2.5G processor 500 megs of RAM, and an older GeForce 5200 card. Performance was (not surprisingly) poor, and once I got into raiding, that machine became completely unacceptable.
Upgraded to a 3.6G Pentium chip with 3 gigs of RAM and a 7800 GTX card. Huge upgrade overall, but even at that, there are still locations/scenarios that can tax your system.
At the time the game was released (11/04) there was really no system out there that would run it well with the detail levels cranked up. This is still mostly true. I can crank things up to the highest detail settings, which works alright in most zones for ambience and screenshots, but combat starts to drop the framerates quickly, and raiding in high detail is still mostly unthinkable.
Also, certain zones (Qeynos Harbor) where people congregate tend to tax your system.
Bottom line, for everyday adventure in EQ2 medium performance settings are your friends.