it depends.
if the mobo has onboard graphics, it might be a good idea to install WITHOUT extra GPU, and then grab a system image just in case you need to reset everything to "ground zero" in the future (store the image on a separate hard drive). then, plug in your card(s), and REINSTALL win from scratch, load drivers, and grab another system image (and store it on a separate hard drive, or at least a separate folder from the other image).
if mobo/cpu has NO onboard graphics (like AM3+) then that kinda narrows down your options, eh!