Don't know about the /Win behaviour. Someone needs to report back.
BUT, in the mac version, when you type a word into the URL bar, it prepends
http://www and appends .com to it.
If it behaves the same in Windows, then domain owners would be doing the whole industry a favour by putting download buttons for it on all their websites, because we'll get all our type-in traffic back that was being hijacked by IE& (to live.com) and FF (to Google).