Sirefef Infection; Need Help

Avast has located two trojans on my computer: Win32 Sirefef-AHF and Win64 Sirefef-A. Can someone please give me guidance in how to clean them off?

This needs further analysis by a malware removal specialist:
Go to this topic http://forum.avast.com/index.php?topic=53253.0 for information on Logs to assist in cleaning malware. Use the information about getting and using the tools and attach the logs here, not in the LOGS topic.