I recently bought a new laptop which includes the Advanced-N 6200 AGN network card. I'm connecting to an Airport Extreme wireless basestation (wifi router). Performance was poor in comparison to the previous laptop (a Dell Inspiron 1520 with a Broadcom 802.11g card.
Over at this page; you recommend using the Intel driver update to ensure the latest driver. I had only done Windows Update, so it is wrong to presume that that alone will bring you to the latest NIC driver. For the driver software version, I was at 13.x, now I'm at 184.108.40.206 (by the way, the update doesn't work in Chrome)
Now, I'm getting comensurate speeds:
Dell Studio 17
Windows 7 Home Premium
So, while I'd like it to be on par, and there might be tweaks outside of what I performed on the page above I don't know about, but on the whole, that's much better.