TechRepublic had an interesting article on Botnets and Hosts file pharming. This is something that most people are unaware of while their computers are being silently used by remote attackers.
http://blogs.techrepublic.com.com/security/?p=738&tag=nl.e036
There are a few tools that I would recommend getting Kaspersky Antivirus 2009 which is a pretty comprehensive threat protection suite.
