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.
"Ignorance is the soil in which belief in miracles grows." -- Robert G. Ingersoll