Advanced System Care Free is the best freeware for system maintenance. It provides a one-click solution to repair, protect, and optimize your PC.
Advanced SystemCare Free provides all the essential functions for keeping your PC up to date, including, removing spyware and adwre, fixing registry errors, preventing security threats, Privacy protection, repairing windows, speeding up system performance, and startup cleanup. 
Advanced SystemCare Free has the Diagnose System Option which provides some effective system optimization tools. It is designed for Windows 7, Vista, XP, and 2000 (32bit and 64bit)
This free PC repair software is a “must-have” tool for your computer. 100% safe with no adware, spyware, or viruses; a PC maintenance program that’s incredibly easy to use
Some of the key benefits of Advanced SystemCare Free include:
High end Registry Clean and Optimization
Safely clean registry, compact registry bloat and defragment the registry for super-fast performance.
Security and Privacy assured
Scans and removes spyware and adware. Prevents spyware, hackers and hijackers from installing malicious items on your computer. Erases and updates your PC’s activity history.
Speeds Up PC Performance and Internet Access
Tunes up Windows by releasing the built-in power of your system. Dramatically improves both system and Internet performance by up to 400%.
Enjoy That New PC Feeling Again New!
Whatever version of Windows you’re running, enjoy that “good as new” speed usually only experienced on a brand new PC.
Extremely Easy to Use
Completes its work with just one click! Scans, repairs and secures your PC in one minute. Provides non-technical users an easy way to tweak system performance.