>It sounds overly complex to me (both from a UI perspective and from a coding standpoint on your part) ... why can't you just put it back the way it was????
Not at all, see:
http://www.levelextreme.com/wconnect/wc.dll?FournierTransformation~2,25,10and imagine having another column with a series of checkbox for the forums you wish to read new messages from. By default, it will be the same as the list of forum for participation but you would be able to uncheck the ones you don't want for reading new messages from.