What wireless card should I get?

I got a new desktop computer but it has no wireless card yet. Im looking for one that can give me at least 300 - 400 mbps. I know the wireless speed depends on your router, ISP, modem and other factors, but right now im getting an average of 300 mbps on my laptop. This is the one im looking at right now

D-Link Xtreme N DWA-556 PCI Express Desktop Adapter
http://www.amazon.com/D-Link-DWA-556...725932&sr=8-11

I need to get a card with a PCIE 2.0x1 slot because thats the only slot i have left on my mother board. Amazon says the speed is only 54 mbps but i think thats on a or b networks. I think Ive read somewhere that this one can get up to 300mbps on a N network. Any help on my decision would be appreciated.

A N network can output 600mbps but can this adapter recieve at a rate of 600mbps?

I checked new egg.com but they dont have a rate in mbps listed for this model. They boast that its 14 times faster than g but dont put it in numbers. I just wanna b sure the COULD recieve more than 300mbps

Mabey its only PCI Express x16 cards that can get faster than 300mbps.

I've only ever seen short PCiE type WiFi Cards unless they're custom made for certain motherboards (like was the case with the ASRock X48 Turbo-Twins WiFi board) and I would imagine you'd need a card that handles simultaneous 2.4Ghz and 5.0Ghz bands; and a matching dual band router to get your target speeds.

Otherwise I'd investigate plugging in a WiFi beacon/repeater to your PC's ethernet port if it has gigabit capabilities, and approaching things that way.