First do what Holomir said and see if it has the extra box listed.
However, I don't believe you will actually be able to put an EQW window onto the 2nd monitor while using a 2nd video card.
I'm pretty sure that when you are running 2 video cards, that only 1 can be running 3d applications at a time, and if you were to move an EQW window over to the 2nd monitor it would in fact need to be running off of the 2nd card so-to-speak, which wouldn't work.
It would work with 1 video card that supports 2 monitors on it, but not 2 I don't think.
Now, even if it does work, its going to be incredibly slow most likely. One of the reasons EQW works is that it since it isn't displaying everything that is happening on the 2nd window, it doesn't need to have a high CPU priority. If you get it running that way, I'm not sure how the 2 displays are going to actually work. Would be a heck of a load on your CPU and video cards anyhow. Especially since the 2nd video card would have to be a PCI video card, in which case it wouldn't be all that powerful I don't imagine.