Hello and welcome to TSF.
This is a malware removal forum, not a discussion forum. This thread will be moved to the General Computer Security section where it will be better addressed.
I am not familiar with Exchange Antigen. Perhaps someone else will be able to provide more information. In the mean time, a google search brought up this information:
http://social.technet.microsoft.com/...1-8e878d0900e5
http://www.google.com/search?q=Excee...ient=firefox-a