Microsoft Windows XP runs a proprietary 802.1x authenticator (so I read) that will not recognize wireless N when windows handles authentication (so I experienced). It scales it down to G. (a software retrodegradation/licensing dagger in my heart!)
When using the client software that came with the wireless adapter, windows recognizes the increased speed with the appropriate 300Mbps recognition (seemed to regularly be 33% to 50% faster than my wireless G signal on speedtest.net despite a 'max' rate on comcast's service). However, The increased signal strength and range were a total fail as my client software was roaming to other signals and screwing up my connection, sometimes requiring a manual switch back to the original connection.
I tried to address this by disabling the windows WZC (wireless zero configuration)(control panel, administative, services), and setting my client program to 'very low' roaming. This kept my computer from trying to connect to different networks now within range, but still there were some periodic complete drops of the wireless signal, which is a solid fail for wireless gaming, wireless netflix, and wireless downloads.
I also just updated my driver to the latest driver availble from the hardware manufacturer (which was actually a different company), and tried a third party wireless access program, which seemed to have the same 'G only' recognition offered in windows wireless management.
Upon checking the wireless N signal, it was completely disconnected despite working just a little bit ago and logging onto this page. I hope the new card doesn't drop out on G signals, too, because I likely will run that protocol for the stability of wireless handshaking running inside the microsoft windows framework. There is an outside chance it is a fault of the card, but wireless N isn't new, windows xp seems to have problems with it, and the card otherwise seems to work splendidly.