What kind of MB do you have? Any other PCI cards installed?

As a simple test, try installing your old videocard. You mentioned you have a 9800GTX+. Are you running SLI? This new videocard uses more physical memory space than your old one.

3 boxing w/ 2GB of RAM will cause you to lag a bit when hitting your swap file. Did this lag start happening after the expansion? The expansion may be using more RAM, so 2GB may not be enough anymore.

Could this be i have gone from running 1 copy of wow on a single monitor and the 2 smaller view ports on a second monitor, To all 3 on a single monitor
I would be grateful for any help
This is probably not the case. Running all 3 instances on a single monitor is easier on your videocard.