Help please?Can Office 2007 Student edition be installed again

if I have to use the recovery CD? It said only three uses on three PCs. There's only one left for me to share. My concern is if I install it now and later I have to do a complete recovery, will be be able to install it again? Do I need the original Office CD to do it? Or anyone can teach me how to do a recovery point to prevent it happen? I got attacked by two viruses alreday and had to buy a recovery CD from Gateway--I didn't make one when I first bought it. Shame on Gateway for charging me money. Thanks a lot.