As “tbennett” says in the discussion, see KB314843.
Using the unattend file to specify “D:\Documents and Settings” is the best method and in my opinion the only method to use for a business environment.
While you can manually move the folder and update most of the items to the moved location, there is no guarantee that you will find everything you need to update. Some items can either encode the location in a binary key or within a configuration file. Hunting all that down and repairing is a major undertaking. A manual move of the “Documents and Settings” root in a business setting where the systems must be stable is asking for random insoluble issues.