I don't know, if it's just me, but I don't like portable applications very much. I'm not very pleased by the thought of carrying around "my" preferences because of several security issues. Don't think right about getting stolen the USB drive, but do I know exactly which personal information is stored where? Just as a weak example :) What about taking a browser to a different machine, logging in to amazon.com or ebay.com or something. Do I know exactly where my credentials and other private data are stored? Just a thought…