The first problem was in the installation instructions. Step 3: "Open the Wireless USB manager". No such program exists, with my install of Vista at least. No driver software came with the hub.
Windows searched for a driver, and found one for F5U302, not 303. It didn't work. (Credit where it's due: Vista said "it doesn't work", something which I usually have to figure out myself)
I contacted Belkin, and they said I didn't need a driver, but the WUSB manager, "software which is a built-in interface in the system by laptop vendor". I asked where this software might be found, since I didn't have it, but they couldn't help.
I am trying to contact PB, but my laptop is out of warranty, which means that I am offically dirt. You beautiful people are my last hope.
How can I get this to work? Is there any kind of mythical universal WUSB thing as Belkin would have me believe? Google has failed to be my friend. Where can I find it?