Got the trial, LOVE the game, getting full tomorrow. Unfortionatly, i do not have a credit card, so i cant just jump up to full. I do have the money to just walk to gamestop and buy it though. So how does this work, can i simply add the registration key from the box and not have to reinstall anything? Or does it have to be harder? Thanks to those who answer, it matters quite a bit, as if i have to reinstall everything, i have to reinstall TF2 also because the downloader is almost 8g for SC2 and i cant delete that untill the full game is done, so i have no room for TF2