SFC checks for corruption of the Operating System (Vista) and may be able to fix the problem.
Chckdsk, looks for errors on the hard drive.
Chkdsk, should be part of your regualr maintenance. SFC, is used primarily to find the source of a problem and correct it.
Quote from one of our tutorials on chkdsk

This will show you how to use and run Check Disk or chkdsk at startup from within Vista, the command prompt, and the registry to check for corruption and possibly repair errors and bad sectors on the hard drive.
Check Disk - chkdsk

Opening statement in this fine tutorial explains SFC
System Files - SFC Command


Regular Maintenace for Vista and for Seven
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