I'm looking for recommendation on a new machine to run my quad box setup more smoothly. I prefer to run all four instances of WoW on one machine.

Here's the problem I have right now. I have all my settings on low, all WoW instances capped at 15 FPS, two-three add-on on main screen and none on followers, but there is still lag when I enter cities or places with more than 10 players. When I do Karazhan or Sunwell, my FPS goes down to around 5 which is nearly unplayable. In Alterac Valley, my FPS drops drastically when I approach a battle. There is also problems in 5v5 arenas when the fight starts. With such low FPS, /follow and spell casting are hardly responsive making my toons cast at different times and the need to click multiple times for spells to work.

My current system spec is as follow:

Operating System: Microsoft XP Professional
System Model: Dimension 9100
Processor: Intel Premium D CPU 3.00GHz (2 CPUS)
Memory: 3326MB RAM


I would like some recommendation for a new computer spec that can handle the following:

1) Max Settings on all four instances of WoW
2) 50+ FPS on all instances of WoW even in extremely populated areas with lot of spells and actions going on
3) 20+ addons ( custom Unit Frames, Auctioneer, recounts meters, addons that are huge resources hogs)
4) smooth video recording (fraps)
5) ability to open even more programs at the same time
6) two monitors

I'm not sure if I'm pushing it or if this is even possible but I would really like to run everything smoothly on one computer instead splitting it between multiple computers.