Transferring PC Details

HI
I have ordered a new PC and have started to move some stuff onto CDs to take
to the new PC. I have got all My Documents and save files for programs, and
wanted to know what else I should keep. For example, how do I backup all of
my Outlook Express settings? Is there a way to copy my messages? Are there
any good websites that explain stuff like this? Is there anything that
somebody didn't take to a new PC but really wished they had?
Thanks for all help and advice
Peter Cavan.