Centrino WLAN

The built-in WLAN card is a normal Intel "Centrino" 11MBit card:

[...] Intel Corp. PRO/Wireless LAN 2100 3B Mini PCI Adapter (rev 04)

There are three ways to put this card into use: There is a commercial
"driverloader" which uses WinXP drivers to talk to the card and there
is the ndiswrapper project which uses the same method
but is OpenSource and Free.

And of course there is the Intel OSS driver project at SourceForge.

I've written two guides on how to enable WLAN using ndiswrapper
or the OpenSource Intel driver:

• ndiswrapper install guide
  
• Intel OSS driver install guide
  

While the Intel driver sure looks promising (it features, Noise / Level / Link information and monitor mode which ndiswrapper doesn't) it still has a long way to go. I experience a ton of lost packets and the connection will degrade over time.

Ndiswrapper is very stable and generally Just Works. From time to time the module fails to load properly and can't be unloaded. Only a reboot helps in this case.