can the graphics card be upgraded on this model from the original 128mb installed? Yes.
if so what is the highest mb card that ut could be upgraded to? 1Gb, or 1024Mb. The best slim card is the 9800GT, however you'll need a good power supply. Grab an HD5570; best low-profile low-power card.
also is there room for extra ram expansion? Usually, it depends on the motherboard.