Our answer: You can't. You can only take precautions to protect your computer and the data it contains. First and foremost is backup, backup, backup. You can't imagine the number of people who have lost everything because 1) they never backed up 2) they never kept the backup current 3) they never tested to see if the backup media and device were functional. And this was before they were hit with a destructive virus.
We must digress at this point for a short tutorial on backup. What to back up? Data. Stuff that is valuable to make the machine operate. Address lists. Anything you have created that you will need to make your computer operative again when it crashes, which it surely will, with 99.99% certainty if you keep it running long enough. You and I are assuming that you have copies of any programs that are used, and that they can be reloaded when needed. If this assumption is incorrect, then where do you get the program? Shame on you if you are guilty of software piracy and don't have the software to reload. You also have an install book, don't you? Showing CMOS settings, drive sizes, partitioning, operating system notes about special settings, CD keys for installing your programs, a list of program install order , and user names and passwords where used. Having this information in a book will help you bring the system back to full funtionality.
Once you have prepared for disaster you can worry about the virus threat if your computing style puts you at risk. If you don't share files with anybody else, don't go on the internet for programs, don't do email, then you can assume that you are not at risk, even though this is not totally true. There have been several instances where virii have been introduced by commercial software. But if you do any of those things you are at risk.
To reduce the risk of infection you should at the least do the following: 1) Have a virus checking software package intalled on your computer. Have the latest version of the virus signatures installed. Then you either have the software running full time, or you use it at startup and shutdown. Whichever way allows you to sleep better at night. 2) Disable script processing in your email package. 3) Accept email attachments from trusted correspondents only and only if they explain the attachment in the text message.
You must understand that you are still at risk. A new virus can appear and infect the majority of the world's computers before the anti-virus software can be updated to stop it. There were several that fell into this category in the year 2000.
This is an ongoing project for Tek-Tip members and visitors. It may contain faulty information and/or opinion. If errors or omissions are noted please forward the correctons to email@example.com so the information can be updated. This is a collaborative work of all of us. Special thanks to: Alt255 Comtech jrbarnett