Immunet is worth a look -
Antivirus, Antivirus Software, Free Anti Virus Download-Immunet Real Time Antivirus
Free to detect malware, subscription required for rootkit removal, will co-exist alongside other AV solutions.
And avoid IE like the plague, use FF with NoScript / FlashBlock, or Chrome with similar.
Disclaimer - I work for the firm which owns Immunet, but as I have a Mac I don't use the product
