Kaspersky TDSSKiller 18.104.22.168 was updated this week and is a popular free tool that will enable you to detect and remove an installed rootkit. Complements your existing security software. Talking of security software, Comodo Internet Security 5.4 was updated this week, along with Comodo Firewall 5.4 and Comodo Antivirus 5.4. SUPERAntiSpyware 4.52 Free was updated, whilst we wait for the final release of v5, due soon.
If you are stuck you will also find http://devbuilds.kaspersky-labs.com/devbuilds to be very useful. In particular, the RESCUE DISK 10 folder contains an emergency boot disk that will clean most virus and root kits.