Assuming it hasn't been removed, any laptop that comes with an internal WiFi card will have an FCC warning/ID sticker on it, usually the bottom. It will be a bit more lengthy then the usual 'this device must accept any interference yadayadayda', and go on to include a FCC ID number. If you have an FCC ID number, your capable of broadcasting something.
Also, every wireless adapter I've ever seen comes bundled with some software, usually some sort of GUI that lets you browse available networks and configure security options .etc. Normally, that software loads on boot, and will at least yell at you that it can't find any open networks in range. It sounds like the laptop does not have a wireless card.
On the topic of USB adapters, I've had great luck with
This guy from Belkin. But, I suspect that just about all the little wireless USB hubs are pretty much the same. It shouldn't cost you more then 20, if that.
-Andy A.