Unlocker
- Unlocks files/folders that are in use.
CCleaner
- Scan/fix registry issues, cleans out temporary files.
Autoruns - Lets you view and change items that load on your computer or run on startup.
Mozilla Firefox
- Simply the best web browser, ever.
Firefox must-haves:
Adblock Plus
- Allows you to block annoying / deceptive ads.
Adblock Plus Element Hiding Helper
- Extends Adblock Plus and allows finer control over what you can block.
NoScript
- Blocks all JavaScript unless you decide to allow it. Stops many annoying web issues. I recommend putting this in blacklist mode (it defaults to whitelist mode).