Low profile = small. That's about it. You pay a premium because they made it smaller for you. If the computer you linked is the one you have, it comes with a 9800GT, you'd be downgrading if I'm not mistaken with the 5570, or at least not getting much of an improvement. The 5770 is a good card, but if all you're playing is WoW, I wouldn't be able to justify getting a better card just for that. WoW isn't a particularly demanding game, so a 9800GT would probably run it just fine. Then again, you obviously know more about the situation than I, so maybe you should go with the 5770.