cpt spam can
7 weeks??? Are you serious? I was starting getting worried because I sent mine off on 23/12/06 and only had two identical emails (1st on 27/12/06, 2nd on 2/1/07) to let me know that they've recieved it. And I haven't heard anything since. But I guess I can calm down if it took them 7 weeks with you!
About your question, I purchased 'Speed Mathematics' by Bill Handley because somebody recommended it somewhere here on either this or the old ctc threat and I think it's brilliant. I could imagine it's not everybody's piece of cake but I'm finding very helpful indeed.