|It depends on how the Laptop is configured.|
Some machines with both VGA and DVI ports will only allow one to be connected at any one time. The only thing I can recommend to do to find this out is to just try it!
Otherwise, yes, a USB-> VGA dongle would work fine.
C2D E7200 @ 3.6GHz
XFX 780i SLI
4GB VData @ 810Mhz
BFG GTX285 OC 1GB w/Palit 9800GT OC 1Gb for Physx
Corsair TX850 PSU