Email is not the only way to get viruses; P2P (file sharing programs such as kazaa, winmx, direct connect etc) is also another way to get viruses.
When downloading programs, the main thing to watch out for is the file size. If you are downloading a program that you expect to be rather large such as a game, don't grab a file that is 10KB, since it's most likely a virus. However, I've been caught with a virus even with large files, so file size is not the only thing to watch, as an exe is still valid even if junk is added at the end, so a 64KB virus will still function even if it is turned into 650MB.
Icons are something to look for too, fortunately, virus writers don't take time to put icons. If your download should be a setup file, you should see the icon of a setup file. If it's just the blank icon that typical plain or corrupted exes have, don't open it.
Another thing to do, which should be obvious, is to scan the file for viruses using updated virus definitions. But don't rely on only your virus scanner, as they are not perfect, and if the virus has not been reported to them yet, they won't know to create a definition for it!
Changing settings to stay safe
If you do open a virus, you want to avoid it going to all your friends. The simplest thing to do is to NOT use the windows address book. It is easy for viruses to get through and Microsoft is not doing anything about it. Just don't use it. Put them in spreadsheet or even better write them down somewhere. Don't use the address book.
Another "feature" to avoid is the auto preview. Some viruses can attempt to open themselves just by opening the email. There are security holes in Microsoft mail programs that allow this. In Microsoft Outlook, click on the view menu and remove auto preview. You need to do this for every folder, but the inbox is most important. In Outlook Express, click on the view menu and go to layout. In the dialog box, you will see a check box for show preview pane. Uncheck it and click ok.
Another thing you should change, especially if you download a lot, is the option that allows you to view the file extension. In Win98, go in any folder, click on view then folder options and choose the view tab and where it says hide file extension for known types, uncheck it. In win2k, it is the same process, but instead, go in the control panel and open the folder options icon.
Avoiding server worms
Some viruses, mostly worms, can exploit through servers and affect other servers from servers that have been infected. A good example is the SQL slammer. This was a worm that affected SQL servers run by Microsoft IIS and Microsoft SQL Server. Once the worm gets in, that particular server starts trying to find more exploitable driving internet connections to a halt in the process. Servers running Apache were unaffected by that, except for the many hits to try to get in. IceTeks received about 100 hits per day when it was run on a dedicated home server. Most hits came from major ISPs and other big websites that had no clue they were still affected.
The simple solution to avoid these types of viruses is to NOT use Microsoft based server software for your server, especially if it is a public server. The operating system is also crucial, but the actual server software is much more. Apache, which is free, is much more secure than Microsoft based server programs such as IIS. IIS may be easier to understand and administer, but it saves a lot of hassle to learn how to use Apache. IIS has a large number of vulnerabilities, such as the ability to gain access to cmd.exe and basically delete the whole drive by doing a ../ request in the address bar. These don't require viruses, but simply commands, but there are worms written to automatically make these commands. The code red does this.
Removing a virus
The best way to do this is to do a clean install. However, depending on how bad the virus is, a simple clean install won't remove it. So to be extra sure, you'll want to do a low level format. This is especially true of you got a boot sector virus, as even repartitioning and formatting won't quite remove it, but sometimes you can get away with an fdisk /mbr, but not all the time. here are various removal tools for viruses, it is good to use them and see if they work, but proceeding with the clean install is recommended. You never know if the virus is completely removed by deleting files you suspect are infected. Some viruses such as the Bugbear will close anti virus programs and other programs to make it hard and annoying to figure out what to do. A clean install is the best way to ensure that it's gone for good.
Viruses are out there, don't be one of the many infected ones! Stay alert and stay safe! Don't open unexpected files, regularly update your virus definitions and scan downloaded files!
I hope this article was useful for you!