If you've purchased a computer, or are just learning about using email and the internet, you may be faced with the problem of abnormal function of PC or system hanging problem very soon.

Somewhere down the line, there will be problems with your computer (adware, spyware, viruses, good software gone bad, etc,). Obviously, you should use protection software to prevent as much as possible. Internet is one the major source of computer virus. Usually they enter your program through an email, or while you are browsing a website.
When these programs run, usually without you knowing, they can cause all types of problems with your computer. Some viruses can be mildly annoying, slowing down your computer as they use your computer's resources for another purpose. Others can be very dangerous, collecting your personal information and sending it to another party, or damaging your hard-drive.
Once you realize that you need anti-virus software installed and running on your computer, you'll have to choose which one to purchase and install. This can be a complicated process, but here are some tips to make it a bit easier.

First, check your computer to see if it came with anti-virus software. Many new computers are shipped with anti-virus programs already to go on them, you just need to turn them on. Check your instruction manual to see if this is the case with your computer.
Check with the vendor. If you purchased your computer from a local retailer, check with them to see what anti-virus program they recommend.

I think that the best way to cure virus/worm problems is to prevent them from happening, and the best way to prevent them from hapenning is through education and awareness. Being a geek, understanding viruses seems to come naturally to me, so I figured I would share information about them with others.
If you are new to computers, please take some time and seek out professional assistance -- the rest of the Internet will thank you for it.
Here's some general tips for staying safe online:

Download and install the Firefox web browser and use it exclusively instead of Internet Explorer. IE is chock full of security holes, and new ones are being found all the time. Using IE is a big liability these days.
Do not open any file attachments from strangers. There are a number of worms which spread themselves this way. The same goes for Instant Messages from strangers.

Do not click on links in emails from strangers. There are a number of worms which spread themselves this way. The same goes for Instant Messages from strangers.

Install anti-virus software on your computer, run it regularly, and keep it updated. You can find some products listed here.
Install anti-spyware software on your computer, run it regularly, and keep it updated. You can find some anti-spyware products listed here.
Back up your data regularly. Besides viruses, there are many other things that can that cause loss of your data, such as hardware problems, software bugs, and theft of physical computer equipment. If you are looking for a primer on backup strategies and technology, I have a seperate article on the subject, available here.

This is not a complete guide to staying safe online. But, if you follow the steps outlined above, you'll make it much harder to get any sort of infection, and you'll be doing your civic duty to help keep the Internet free of viruses, worms, and spyware.