I received my refurbished unit recently and noticed I couldn't connect to an N wireless network. In the card's settings in the device manager, only a/b/g were listed. I checked the card itself and it was marked with the following:

Intel Model: 512AG_HMW
Intel WiFi Link 5100
D P/N 0KW380

Researching this online, I saw a few 512AG_HMWs on ebay in the UK and Australia, and the ads didn't mention "N" anywhere. I continued searching and found a spec document on Intel's site which clearly lists the various renditions of this card. These are the relevant ones:

 

512AN_HMW (supports 802.11a/b/g/Draft-N

 

in in a PCIe Half Mini Card form factor)
512AG_HMW (supports 802.11a/b/g in in a PCIe Half Mini Card form factor)

The order detail states that the laptop contains:

  1   Intel WiFi Link 5100 Wireless N Half Mini-Card

Anyone else seen this? When I get it resolved, I'll let you know whether it's easy to determine within Windows.