Peter,
Normalization is part of the termnology associated with relational database theory. There is a lot of information about it on the Internet. Here are the results of a search I did:
http://tinyurl.com/5aahl As Loren says, everything is a trade-off. What you gain in performance, you pay for in extra disk space. You need to find the optimal solution, given your requirements and limitations. As Jeanne says, if you want us to help you find your optimal solution, then you need to supply us with details of your requirements and limitations.
Good Luck,
Avi.