If you have a friend with some extra discs (or find a freebie download - but be careful), yes, you can install it on your comp and play. However, you will only be able to access the same content you have on your Xbox360. As Karbuncle said, the expansions are linked to your account, not your system. If you buy a complete comp version and don't have any Abyssea expasions on your xbox360, you'll be able to play Abyssea on your comp but not your xbox. If you're missing any of the current expansions, you're better off buying an xbox360 copy and finding somewhere reputable to download the game for your comp. In any case, the $10 steam version would be a good buy if you've got $10 to spare.