You can get WiFi PCI cards for desktop PCs as well. The WiFi network they're setting up around Freddie only serves the downtown core at the moment. I suspect they'll make it out to the trailer parks round about 2030 or so. On the other hand, I have now access to three wireless networks with my laptop, the ITC building at school, coming in through my lab's window, the Freddie public wireless network, and the 802.11b router sitting on top of the bookshelf in the upstairs hallway of my house.

Greg's quite right, though, PCs are evil. Thus I would recommend an iBook. They have G4 processors now, can be taken around, and used with wireless networks galore. They're a chick magnet. And no worrying about viruses or spyware. Also, you have a built in Unix command prompt and X-Windows server, so you get all the power of unix without diddling around with the silliness of Linux compile / configure / fix the broken dependencies that some people seem to find more fun than showering or going to the barber.