Being an instructor, I would recommend taking a class at a junior college
somewhere. The price might be more affordable than some of the major
training firms, but try them out too.
I also like the Step By Step Book Series by Microsoft. It is divided into
chapters that are timed at about 30-75 minutes depending on the subject.
Lots of hand on exercises
Check out the following web site for the 2002 version of Excel
http://www.microsoft.com/MSPress/books/5051.asp