This sounds good in theory, except that it ties you down to a single computer.
There are so many ways around this "problem" portableapps dot com for one, password keeper apps (Password Gorilla works on all 3 major OSes), synced bookmarks with Delicious is my current setup - but I have had a few over the years. Now "ties you down to a single browser" or "requires you to have your USB drive with you" I would agree with - but not a single computer.
"They that can give up essential liberty to obtain a little temporary saftey deserve neither liberty not saftey." -- Benjamin Franklin, 1759