Even if you have an Anti-Virus program you still might not be safe. Hackers write and spread new virus files before the anti-virus companies can write defenses against them and before you download those updates. That attachment you just received might be ok ... but then it might not.

Examine it first before you click on it:

• Is it the right kind of file? A .jpg or .gif file should be a safe picture file. Same for a .txt text file or a .pdf Acrobat file. But, a .exe file might have a virus, and a .vbs attachment is almost guaranteed to be dangerous!

• Would I expect this from the sender? A gruff ex-crewchief won't send a love letter to all of us, and none of us would send "spam" or porn links. A virus often makes a computer send infected e-mails without the owner's knowledge. If the message seems out of character, it might be infected.

Here are some of the file extensions that you should never open:

Also, some Microsoft Office products can allow scripts to do nasty things with macros. Some of those extensions are:

Most .doc and .xls are safe. Still, make sure the e-mail message "makes sense" with the .doc attachment, and set up Word and Excel so that they don't automatically run macros.

One more thing: your computer might not show you what kind of file you have. Be sure to set up Windows to show file endings so that you know exactly what kind of file you're dealing with.