Some systems will handle two monitors, I don't have any specific
information. It's worth a try to re-install the GT520 but I don't think you
will be able to directly find and install drivers for the baulky card. It
may, however, be possible to download them from the NvIdia website and
install them this way. If you have a second monitor it would be interesting
to have both attached to really see what's happening.