CCleaner

This is a great tool to help with cleaning out old temporary files as well as a registry cleaner. Not only does it work well, but it is free to use.

http://www.ccleaner.com/

Sticky Password

I recently went on a quest to find a password manager. I tried a number of designs, some free, some for purchase, and for me, the best was Sticky Password. Of those I tried it was the most flexible and easiest to use.

http://www.stickypassword.com/

Notepad to the Extreme

As a developer you can't beat this tool, and best of all it's free.

SourceForge.net: Notepad++

Launchy

This is by far one of my favorites. You just start typing the name of the software you want to run. Launchy finds the closest match, hit the Enter key and you're there. It's great for people who spend more time with their hands on the keyboard and less using the mouse.

SourceForge.net: Files

Windows Folder Sizing

SourceForge.net: Folder Size for Windows

Free Antivirus Software

Works great. Easy to install and operate. Does not seem to slow down my system. And best of all the Home Edition is free.

FREE avast! antivirus 4.x Home Edition, anti-spyware & anti-rootkit for Windows

Several Useful Tools

This is an article from Joel over at BizzNtech. I found several of the suggested tools to be quite useful. My favorites were Piky Basket, QTTabBar, Visual Task Tips, FileMenu Tools, and Folder Box. Hopefully you will find them useful as well.

15 Essential Windows Explorer Addons | BizzNtech