The Intel IPW2200 wireless chipset has an open-source driver but it requires closed-source firmware; therefore the driver until now has not been in the standard LinuxKernel. This will be changing to be included in the LinuxKernel with a path specified for the firmware. This is coming RealSoonNow.
This chipset is used in many laptops (such as the Compaq Presario series) as part of the "Centrino" brand.
Ubuntu Linux (5.04) already comes with support for this wireless card out of the box, so you should be all ready to go. However, the older version of the driver that comes with Hoary does not support WPA properly, so either manually compile and install the driver from the above link, or use Ubuntu Breezy (currently in development). See the WirelessNetworkSecurityNotes for more.
You can download the driver (and the firmware) from http://ipw2200.sf.net, although you will also need to build the ieee80211 support modules which are currently outside of the kernel tree (I think there is a version of them in linux-2.6.13-rc1, so it might be a part of future releases).
ipw2200: Firmware error detected. Restarting.
20:29:42.542584 00:13:10:6c:96:xx > 00:12:f0:8e:e7:xx, ethertype Unknown (0x888e), length 135: 0x0000: 0203 0075 0200 8a00 1000 0000 0000 0000 ...u............ 0x0010: 5730 ce72 b567 7242 1b5b acfb 21d5 2442 W0.r.grB.[..!.$B
Using Ethereal instead of tcpdump showed that these packets were EAPOL/encryption key something-or-rather.