An up to date Linux box!!!
Or, an unplugged Windows box!!!
Most signature based AV tools only catch about 50% of the bad stuff out there. And, they only catch what they know about in their latest signature update. That stated, anything with a good real-time engine, up to date signatures, regular full system scans, and using common sense while on your computer will help out. McAfee has worked well for my friends. Norton, not so well...
