There is a description on the Microsoft Malware Protection Ceter -
http://www.microsoft.com/security/portal/SearchResults.aspx?query=Win32%2FDelf.ER and more here -
http://search.live.com/results.aspx?q=Win32%2FDelf.ER&Form=IE8SRC&src=IE-SearchBoxWhen searching for malware information you get better results searching for only the name without the classification. For example search for Win32/Delf.er not Trojan: Win32/Delf.er.
Jim - MVP Windows Live - Forum Moderator - Live One Care - Live Mesh