Antivirus software is the classic PC utility that has always been thought of as absolutely necessary if you own a computer. The fact is, in Windows Vista, the need for antivirus software when User Account Control is turned on is significantly lower than in Windows XP because UAC prevents most events from happening that you have not authorized. For example, if you open an e-mail that contains a virus and the virus attempts to reformat a drive, a UAC prompt will pop up asking you to confirm the reformat request. UAC stops the virus dead in its tracks in this situation.
Unfortunately, many people choose to disable UAC in Windows Vista, and UAC will not protect you from all types of attacks. After all, sometimes users click Authorize on every UAC prompt they see, which makes UAC useless. For this reason, I feel it is still a good idea to run some type of basic antivirus program on most computers-especially if you have UAC disabled or if the computer is used by beginning computer users.
For more information on UAC, refer to Chapter 14.
There are many free antivirus utilities that work well with Windows Vista. My favorite is avast! 4 Home Edition, which can be downloaded for free if it is for home use. This saves a lot of money that you may be spending on mainstream antivirus products and their yearly signature update fees. With avast! 4 Home Edition, all the signature updates are free. All you have to do is register on avast!'s Web site to get a free registration key within 60 days of installing the software.
Similar to other popular virus scanners, avast! has various on-access scanners that automatically scan files when they are opened on your computer. This makes it less necessary to do a full system scan to find files because you can be sure that a file is scanned before it is executed. Additionally, avast! includes support for all the popular mail applications, so you can be confident that your messages will be safe as well.
Using avast! is slightly different from other antivirus programs. Follow these steps to get it up and running on your computer and to perform a full system scan:
Visit http://www.avast.com/eng/avast_4_home.html and download a free copy of avast! 4 Home Edition.
Once you have it installed, reboot.
Click the Start button, type avast in the Search box, and then press Enter.
Enter your registration key if you already have it; otherwise press the Demo button. avast! will now perform a scan of running applications in memory.
When the in-memory scan is finished, you are ready to set up a full system scan. To do this, you first need to select what will be scanned. This can be done by clicking the drive button located on the top of the right column of buttons, as shown in Figure 15-8.
Figure 15-8: Selecting a full disk scan in avast! 4 Home Edition
Click the Play button on the left of the screen and the scan will begin.
After the scan has completed, you will be presented with the results and the option to take action on any discovered viruses. With the active protection features of avast!, you do not need to run a full disk scan very often. If a file becomes infected and you attempt to open it, the onaccess scan will catch it.