Doing 2D based desktop computing is not going to cause any sort of bottleneck nor should it be causing issues like this. Its possible, but unlikely
Do you have the actual nvidia driver installed jclark or just the one windows installed? Generally the one windows installs is a generic one from nvidia and may not work all that great, try going to the link Mike posted and downloading the latest one right from nvidia
THat 6200 should be able to handle what your doing, hell I have an old AMD XP system with a GeForce 5200 that can run dual monitors without issue
Start with installing that driver and well go from there