I only run Windows in a Linux virtual machine. If it gets a virus, I just revert to the last snapshot. That said, I do run ClamWin (ClamAV for Windows), but it only runs scans when I want, such as when I think that something is trying to get in my "pants". I do AV cleansing for clients, but I use ClamAV and 2 other professional-level scanners on a Linux system. I connect the infected drive to my linux system using a docking bay, make a bit-image backup of the drive and file systems, and then scan the file system images with 3 scanners (I don't touch or mount the infected drive/partitions) - each generates some false positives, and each catches viruses that the others don't. Then I clean the system. This costs my clients $$, but they get back systems that are clean, and their data is intact.
Just like there is "safe sex", there is "safe computing". Here are a few simple rules.
1. Don't download and open email attachments from people you don't know.
2. Don't download and open email attachments from people you do know unless you have scanned them first.
3. Don't respond to spam messages, and don't open them except in a "sandbox" environment, such as gmail's spam folder.
4. Make sure your internet browser is kept up to date, disable java plugins, and make bit-image backups of your system at regular intervals. That way, if you do get infected, you can revert to a "known good image".
5. Keep your user data on a file system or device separate from the system. IE, system stuff on one drive/partition, and user data on another. This is called "separation of domains of responsibility".