As an anti-virus and internet security solution, Avira has recently been useful.
Just today, a client asked me to get rid of the dreaded Windows Rootkit virus. USing the free Avira AntiVir Rescue System LiveCD, and later, Malwarebytes Anti-Malware in Windows safe mode, I was able to complete that task within 4 hours.
Then after using CCleaner, I also found a trojan that runs at start up. The trojan was given the process name of NFIJUGARORO, yet ran an executable named ipoyamuzage.dll. This particular bug also required me to use regedit to carefully delete it.
Avira: http://www.avira.com
Malware Bytes: http://malwarebytes.org/
CCleaner: http://www.ccleaner.com/