Everything - File finder. Finds files instantly. Honest. Often before you finish typing the name.
JBMail - Email reader. Doesn't download emails (unless you tell it to). Leaves them on the server and shows you the headers. Double-click to read. Since it doesn't download them all, it's super fast. Can be set to strip away everything except text so that you Never get a virus from the message body. All the basic functions -- address books, reply, attach, spam filters, etc.
WinPatrol - Monitors critical files, registry, startup, etc., tells if you something messes with them. Lets you delay the launch of some of your startup programs, for faster booting. Many other functions. Easy to use.
ERUNT - Backup and restore the registry.
Exact Audio Copy
Sandboxie - Run your browser, or any other program, in a sandbox. If you get malware, just delete the sandbox and your real system is untouched. Easy to use.
VLC - Media player that reads virtually every format. Launches quickly. Functional real-time controls for color, brightness, playback speed, etc.
SharpKeys - Change any key to anything else. I made the irritating CapsLock key into an extra Alt key.