I knew there had to be a way to do this.
So you go fullscreen with eq2 in 1 monitor, but the second you click on something in the other monitor eq2 drops out of fullscreen. well try this:
In windowed mode, click the maximize button.
press alt enter
click in the other monitor
The screen will flash like it's going to drop out of fullscreen.. but then....it wont!
also, in the second monitor (mine is on the left) you should see a line on the right side, you can drag it and eq2 will span both monitors in full screen! good luck powering it...
edit: ok it will span both monitors by horribly distorting your veiw, it looks impressive tho. and when/if they ever add veiwport, it'll be good for interface peices.