There are some basic rules that we must all follow that will help to keep viruses out of our computers. These rules are not an absolute cure, but the help allot.
1. Do Not click on Pop Ups. (This one is a never do)
2. If you receive an e-mail from some one you do not know, don't open, just delete it.
3. Do Not open e-mail attachments from people you don't know, or from people that usually don't send attachments. In the latter case, I would call these people before I opened the attachment. (Remember, a "trogen" can send from your own address book, so the person receiving the e-mail will think that it is coming from you.
Just a word of warning. Younger folks do not realize just how dangerous the internet really is, so we must talk to them constantly so as to help them be safe.
You didn't say what e-mail client you use, but most have security settings that can help. Outlook Express and Windows Mail can block attachments and graphics. To do this open the mail client and click Tools>Options>Security. You want a tic (check mark) in:
1. Restricted sites zone.....
2. Do ot allow attachments.....
3. Block images and other ext.....
With the above security setting Windows can help quite allot in keeping viruses and other nasty stuff out of your computer, but it will make the mail client a little less functional in that your kids won't be able to send pictures, etc back and forth.
Last, be very careful with social network sites like Facebook and My Space. Nasty people post nasty things for downloading. Also, be very weary of P2P sites. These sites post music and software that can be downloaded for (free), but remember there really aren't any free lunches. I have seen way to many system infected with very bad viruses ans malware that was downloaded along with what these folks thought was "something for free".