We were in the same position. Not sure why Upgrade Advisor did not tell you about *=. In any event, you can either convert these or run 2008 in compatibility mode 2000 (i.e. 8). If you can, convert these!
In any event, here is a query to identify these:
(SELECT type_desc FROM sys.objects O WHERE O.Object_ID = M.OBJECT_ID),
(Definition LIKE '%*=%' OR Definition LIKE '%=*%')