Why getting lag with the comp i have?

I recently got a new computer (spent a pretty penny on it) and upon trying to run 2 coppys of wow i got some horrible lag and frame rate loss. Here are my stats.

Operating System: Windows Vista™ Home Premium (6.0, Build 6001) Service Pack 1 (6001.vistasp1_gdr.090302-1506)
Language: English (Regional Setting: English)
System Manufacturer: VelocityMicro
System Model: VelocityMicro
BIOS: Default System BIOS
Processor: Intel(R) Core(TM) i7 CPU 940 @ 2.93GHz (8 CPUs), ~3.2GHz
Memory: 6132MB RAM
Card name: ATI Radeon HD 4800 Series
Card name: ATI Radeon HD 4800 Series

i noticed that the memory use and cpu use are BELOW 50% when both WOW's are running. Im tottaly stumped. PLEASE HELP

couple questions...32 or 64 bit OS. 2 video cards? both would point to problems

64 bit and yes i have 2 radeons

crossfire will slow WoW alot, I hear Windows 7 has a fix in it. Try it on one card.

tbh im very new to the multi core/card computers and dont even know were to start on vista to do anything with my hardware. have and sujestions were i need to start? also do i need to configure my i7 CPU? i notice that one of the cores seems to be running at 50-70% all the time and the rest arn't doing anything. when you say windows 7 thats a patch correct?

1. Disable crossfire



2. Edit your Config.wtf file with Wordpad. You can find the Config.wtf file in your WTF folder inside your WoW directory

Once you have the Config file open, look for a line that reads SET processAffinityMask "X". X should be 255.

3. Save the newly edited config file and re-launch WoW.

Also... Turn down the shadows a bit inside WoW. For some reason, they slow things down big time.

THANK YOU ALL SO MUCH :-D!!! everything runs so much smoother :-D now to stress test it and see how manny wows i can run at once. . . .