First off—before you open any attachment, make sure you know who sent it. Even if you do know the sender, if you aren't expecting it, you might want to send a quick note to your friend and make sure they really sent it—especially .pps files since they can contain viruses. Also, do not open any attachments with .exe, .scr or .pif file extensions.

Nothing worse than getting a file from a friend and you don't have the right program to open it. Here are some common file extensions and the programs needed to open:

.doc - Microsoft Word

.pps - MS PowerPoint

.xls - MS Excel worksheet

.wpd - Corel WordPerfect

.pdf - Adobe Acrobat

.jpg - JPEG graphic file

.zip - Zip (compressed) file

.sit - Stuffit (compressed) file

.scr - Windows Screen Saver (DO NOT OPEN)

.pif - Program Information File (DO NOT OPEN)

The good news is that most software developers offer freeware viewers that will allow you to see, but not alter, content. NOTE: These addresses are long, so you may need to copy and paste into your browser if it breaks into more than one line.

.doc - Microsoft Word Viewer http://www.microsoft.com/downloads/details.aspx?FamilyID=0e56d944-38f6-4eb5-aca6-8bd280d5e6b1&DisplayLang=en

.pps - PowerPoint Viewer http://microsoft.com/downloads/details.aspx?FamilyId=D1649C22-B51F-4910-93FC-4CF2832D3342&displaylang=en

.xls - Excel Spreadsheet Viewer http://office.microsoft.com/downloads/2000/xlviewer.aspx

.wpd - Wordperfect Corel no longer offers a viewer

.pdf - Acrobat Reader http://www.adobe.com/products/acrobat/readstep2.html

.jpg - You can view these in your web browser or most imaging software.

.scr - USE CAUTION if you receive a screen saver via email. They can contain worms or viruses.

.pif - DO NOT OPEN! This is most likely a virus. Clicking it will run a program or code that can mess up your computer.

As for compressed files (.zip & .sit), you can Stuffit! No, I'm not telling you off...Stuffit Expander is a great program that will open most compressed files. http://www.stuffit.com/expander/

There are also a million freeware/shareware programs for opening .zip files such as WinZip. In addition, with Windows XP you can save any zipped file to your desktop or a folder and access the files without unzipping.

So, next time you get an attached file in your email but don't have the program to open it, just grab a viewer.