You want to limit the defrags, so you will not wear out the hard drive. Here are some additional pointers.
To maintain your computer 10 Tips on How to Properly Maintain Your Computer
Steps that I did not notice on the guide include:
Running a scan disc before doing a defrag
Using Microsoft Security Essentials and Malwarebytes.
Making System Restore points, at least once a week
Makaing a system Image once a month (varies by user)
Not relying on your A/V common sense, should prevail. You know of many sites can cause a problem.
Do not use any reg cleaning or optimizing software.
Download and use Ccleaner about once every two months. Untick any registry entries. http://www.piriform.com/
If you follow these instructions, you will be trouble free for a long time to come.
Be sure to back up your hard drive about once a month (varies by user) and to keeep system restore points up to date. Optimize Windows 7