well...the way i go about it is using XP's Files and Settings Transfer Wizard, as it will take all of my settings, outlook/outlook express emails/boxes, Internet favorites, etc, and puts them in a .dat file. Move this off to a CD or across a network (cd is preferrable).
then find all your documents, saved games, etc.
DO NOT ATTEMPT TO SAVE THE ACTUAL GAME OR PROGRAM. YOU CAN SAVE ANY FILE CREATED WITHIN THAT PROGRAM OR SAVED GAME!
things like MS Word docs, spreadsheets, text files, Diablo2 saved games, etc. Pictures. Movies. Music. Anything that is important and you do not have an installation cd for or you dont want to download again. heh...pr0n can be considered important if it is uh...'educational' =)
You wont ruin any hardware by attaching it to the new computer unless at the same instant a lightning bolt slams into your power line, or aliens drop an EMP bomb on your house =)
mainly just make sure you have SP1a and the worm/blaster patches on a cd before you even install Windows again (and again, very important, if you dont have a hardware router, please install a good firewall like Zonealarm or Sygate before going on to the net...you will become infected almost instantly the first time you go for WindowsUpdates!).
To learn how to slipstream SP1a into an existing non-SP WindowsXP cd, read this:
http://www.windows-help.net/WindowsXP/winxp-sp1-bootcd.html
It works like a charm!
Again, please dont hesitate to ask if you have any other questions!
Travis
PS, if you haven't noticed, im your official DFI support tech =)