[RESOLVED] Can someone help me with a List comparison?

[boops boops]

I have a class called "ImageThumbnail", one field of which is an IO.FileInfo object. I have one ListA =List(Of ImageThumbnail) and another List B =List(Of IO.FileInfo).
I want to find all the ImageThumbnails in ListA whose FileInfo isn't in ListB.

I can't work out the right syntax to do this, despite all the examples in MSDN. I don't think I can take advantage of List.Contains because the FileInfo in ListA won't be the same object as the one I'm interested in in ListB; it will just have certain field values the same. So I have written a Comparer for FileInfos which overrides the Equals method, and that means I can use FileInfo.Equals. But I can't figure out how to fit it all together.

Any suggestions gratefully received. Cheers, BB