@ Anonymous
Sorry I had to address you that way, but then that was the way you preferred 🙂

1)There’s nothing in particular that you gain by using Ubuntu solely for internet.Well yes, if once you have some issues with connectivity in Windows, the live cd with an active internet connection proves to be a mighty tool.
That said, Ubuntu is pretty bland without connectivity to the net. To exploit various features of the OS you need to be connected to the network!

2)I’ve never tried connectivity through USB. It shouldn’t be much of an issue resolving it though. Ubuntu has evolved to be pretty much a layman’s OS of late.