Relocating the "users" root directory

I have seen this question asked (and misunderstood) in a number of places,
however, I have yet to see a sensible solution.

I suspect like many other people, I have a smallish disk (40GB) for the OS,
and a largish (1TB in my case) disk for data etc.

The user location in Vista defaults to C:\users\<username>.

I have currently 3 users on my machine, and intend to add at least another
3. I want to store user data on my large data drive (D.

I know, that I can use the location tab, on most of the directories, to
change the location of, and copy the files to, D:\users\<username>, however,
for half a dozen users, that is a long process, and there has to be a "better
way"

I have tried setting a homepath to d:\users\<username> but that doesn't
work. I know that I could probably set a batch file, to SET the %USERPROFILE%
string for each user on startup, however, that seems a somewhat retrograde
step.

I have had a look in the registry - there is a key which is at:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList

with a value of : %SystemDrive%\Users

Has anyone tried changing this (and the other associated keys at this
location)?