Cheap upgrade 3rd monitor

Hey guys, I have been needing an entire system upgrade, but that is funded by my parents who think I don't need to right now. So I have had this 3rd monitor sitting around since my system only has 1 PCI x16 slot. I have 2 PCI x1 Slots and I was thinking, should I get a x1 video card to run the 3rd screen only? Obviously not for gaming, but would it be enough for youtube and etc? I was thinking of this one, 

I currently have a GeForce 8400 GS, (old I know) and its good enough to multitask on 2 screens. It disabled my internal video card too , so I can't use that. would getting a second graphics card even work?

Thanks in advance