Pior, I've been looking at this topic myself.
It's possible to get a signal split device, so you can output 2 images on 3 or more monitors. This works fine as you probably don't need to view 3 different screens at the same time. However you're of course limited to the duplicate-image monitors having the same resolution, which can be a bitch.
I currently have a desktop lcd and a 40" lcd tv. I want to set up another desktop lcd and a cintiq.
lcd desktop A = 1680x1050
lcd tv = 1366 x 768
cintiq = 1600x1200
... non-matching resolutions
Found any good sites for info on 2+ screen outputs? Know whether it will mess with performance?
EDIT: Ah, Whargoul, your cintiq is 1680x1050 . If one of your LCDs are too maybe you'll want to output 2 desktop images like you're doing now, but clone one of them onto the cintiq by splitting the signal off of the cable.