The superhub 2 is a 2 stream router on 2.4Ghz and 3 stream on 5Ghz. You didn't say if this was a dual band card. Which two cards are you considering?
If you are thinking about 5Ghz, how close to the router will you be? 5Ghz doesn't penetrate walls as well as 2.4Ghz. If you live in a congested 2.4Ghz environment (appartment complex, student housing, etc) then 5Ghz might still be better than 2.4Ghz. If you live in a detached house with few WIFI neighbors, then 2.4Ghz would be OK and the 2 antenna (streams) card would be fine.