One of my favorite programs is Norton System Works. I've been using for years on my own computer as well as my client's computers.
In addition to fixing problems found in Windows, it also has some other useful utilities. One of these utilities is called, Speed Disk - which is similar to Defrag, only it works a little more efficiently. Disk Cleanup is another nice utility. There are more utilities that come with the Norton System works that make it worth it's money.
The only complaint some people have about the software is that it slows down their computers some because it runs in the background. I've never noticed these problems on my computer. But the nice thing is that even if you install it, you can disable the program from running in the background - and only use it when you want to. This will solve the problem of it slowing down the computer.
I've been using Norton System Works for years and highly recommend it to others.