These are the things I can think of.
All your personal files (usually in My Documents)
Any mp3s, digital photos, movies, videos, drivers etc that you may have downloaded.
Anything in your "shared" folders
Any programs you may have downloaded.
All your IE favorites (if you use IE) or Firefox favorites.
Any emails if they are not on the server, plus any e-mail setup info like pop3 and smtp address.
Note any userids and passwords you use.
Remember any special programs you use (look in add/remove programs to make a note of them)
Any picture you use as a background on your desktop.
Cannot think of anything else.
Good luck.