How does the pixel math work with multiple instances of wow running, at different resolutions? Would it be (800x600x4) + (whatever resolution my main screen is) = total?

Im wondering if I can get more mileage out of the video card by tuning down the resolution alot. Would that idea make the 30" monitor work well? And the same would go for the 22" inchers obviously. Im debating returning my 22s this morning and getting a 30 =). Thanks for the feedback.

Also, is it even possible or does it make sense to tune a 30 inch down that much?