Sorry. This was my error. Because it has no drivers, the device with the antennas (your wireless network adapter) is in the "Other devices" category rather than the Network adapter category. Your conversation with Xircal started along the road to identifying it, but you got sidetracked with the discussion about the motherboard.
The 3 antennas definitely suggest that you have a wireless adapter. However, the Linksys WMP600N only has two antennas ... so that's not what you have. Nevertheless, it's possible that the drivers for that device will work with your adapter because they apparently have the same chip. It would be better, however, to get the driver that is specifically intended for the hardware that you have.
The "1394 Net Adapter" is a FireWire adapter. This is hardly used any more. It was Apple's attempt to provide an alternative to USB. LINK
The "NVIDIA nForce 10/100/1000 Mbps Ethernet" is the Ethernet adapter (built into your motherboard).
Neither of the above is a wireless adapter.
Please list all of the items in the "Other devices" section of Device Manager.
I don't know if Device Manager will provide enough information about the "other devices" to identify the make and model of the wireless adapter. When you said that you couldn't confirm that you had the Linksys adapter, did you open the computer case and look at the card? If not, that's the best way to identify it -- there should be a label somewhere on the card.
If all else fails, perhaps you could call your friend and ask what type of wireless adapter he installed.