How to make your pc software and operating system in tack forever, and will not harm from virus. In addition, even without using antivirus at all. You need the following.

The first thing that you'll need to have for this is:

Deepfreeze

You can download it from here.

Windows 7 32 or 64 bit OS

Windows XP

The second thing is:

While installing deepfreeze, put it in mind to only freeze the system part of your drive.

And for the final requirement is:

Use our auto-save application. This application helps you automatically saves any save data even your drive is under frozen mode.

You can download this application here. Or you can order us your very personal type of application here.