All I had to do was modify that interfaces file and suddenly, like magic, the laptop's built-in wireless started working.

There's this other odd thing happening now, though. Every time the laptop boots up it seems like it kicks all other computers off the network. My Windows XP machine, for example, suddenly loses the ability to even ping the Linksys router. I have to actually unplug and restart the router in order for all the machines to be able to access the internet again.

I wonder what that's about. The other two machines are connected to the router with ethernet cables, so I wouldn't think it was an issue of signal interference or anything like that...