Microsoft Security Essentials are available for Vista. Why not download and install them? After all they are free. The download is only 6 Megabytes and is easy to install. Even if you have another antivirus application, this is another tool in the fight against spyware and malware, and yes, viruses.
“Microsoft Security Essentials provides real-time protection for your home PC that guards against viruses, spyware, and other malicious software.
Microsoft Security Essentials is a free download from Microsoft that is simple to install, easy to use, and always kept up to date so you can be assured your PC is protected by the latest technology. It’s easy to tell if your PC is secure — when you’re green, you’re good. It’s that simple.
Microsoft Security Essentials runs quietly and efficiently in the background so that you are free to use your Windows-based PC the way you want—without interruptions or long computer wait times.”