To help identify whether a pop-up or other warning is real, or whether it might have come from one of the many, many fake scams, Sunbelt Software yesterday put out a short guide. While it only lists a few relatively basic steps (check against a list of known bad apps, run a Google search, etc.), it's still good info to have.
http://sunbeltblog.blogspot.com/2009/06/beginners-guide-is-that-real-anti.html
Direct PDF link download:
http://www.sunbeltsecurity.com/dl/Is%20it%20a%20real%20anti%20malware%20product.pdf
Last edited by Doctor Inferno on 12th April 2010, 2:41 am; edited 1 time in total