I'm doing a (long overdue) rebuild of my Toshiba M200 to get rid of any Beta1/Beta2/CTP/RC gremlins.
Here's the process I use, as well as the checklist of things to install (in no particular order)
0. Backup the data that live on my HDD and are not replicated elsewhere. I use folder redirection for my My Documents folder, so all that lives on a server somewhere that's backed up, volume shadow copied and generally made available offline. I use the Files and Settings Transfer Wizard and also do an xCopy of my working folders to an external HD
1. Install the base OS from the media or the network (in this case it's from my VISTA CD burnt from the internal share)
2. Install Patches, SPs and Hotfixes (Microsoft Update is your friend)
3. Install Anti-virus
4. Join the Domain
5. Install all the Apps