I am running 12.10x64, 16 gigs of RAM. I am currently using a 2-monitor setup on an ATI Radeom HD 7750. My computer also has a built-in Radeon HD 4200, which I currently don't use. I am using the fglrx drivers.

My question is this: is there any way at all to attach a third monitor to the Radeon HD 4200 and make some use out of it?

In Windows I am able to do so without any particular setup. However, I don't know how to go about doing it in Ubuntu (or even if it is possible). This is further compounded by the fact that the HD 4200 is no longer officially supported in new fglrx Catalyst releases. Windows seems to be able to load different drivers for both cards, but I don't know about Ubuntu.

Is this at all possible using fglrx?
If I used the open source drivers instead of the proprietary drivers, would this be possible?