The fine folks at PortableApps.com have put together an excellent Portable Apps Suite that bundles eight essential Windows apps that you can take with you on a USB drive. The included apps are Firefox (web browser), Thunderbird (e-mail client), OpenOffice.org (office suite), AbiWord (word processor), NVU (web site editor), Sunbird (calendar and tasks manager), FileZilla (FTP client), and Gaim (IM).  The suite comes in two flavors: Standard, which includes all of the above and fits on a 256MB drive, and Light, which omits OpenOffice.org and fits in 128MB. Brilliant.