The upgrade to SBS2K3 should have been pretty simple. Things that got me were:

1. ISA problems with web proxy. You don't expect this when the version stays the same but it happened.
2. New profile on XP. I did not intend it but I did not re-use my existing profile. For some reason my profile ended up being whuber.wehubconsulti versus whuber. It broke a couple of things so I had to perform some quick copies and re-installs.
3. I had export .pst files of my mailbox, the public folders, and my rules. It took me a little while to set up the permissions to re-create the public folders. I tried to start up Exchange 2003 with the converted  version I had saved but Exchange puked. So I went to plan B.
4. I had to change my SMTP server settings. It wanted HELO versus EHELO.