Just out of curiosity a script we've been using recently to upgrade GroupWise clients from version 7.01 & 7.03 to 8.0.1 HP1.

The script first uninstalls the old version, runs cleanit and then installs the 8 version and does a reboot. Script is run during logon and while users have full admin rights on the workstation (temporarily for this upgrade).
Only XP workstations (SP2 & SP3) in this situation.

So far this has resulted in upgraded clients running smoothly, but I'm still waiting for appropriate feedback.

What I'm curios about is how you are pushing the upgrade to your Windows clients.

Here's the script (still needs a good cleanup):

@echo off
REM # This script needs to be run with local admin rights on the workstation.
color 0e
REM # Silent deinstall using :  msiexec /x <productcode> /q /passive /norestart 

echo.   Removing the GroupWise 7.x Client 
msiexec /x {0555184D-82B5-4DA9-95E2-8BF821C95337}  /q /passive /norestart 
msiexec /x {0555184D-82B5-4DA9-95E2-8BF821C95337}  /q /passive /norestart
msiexec /x {B9A93A85-1997-4381-8979-4B0BB28AEBC7}  /q /passive /norestart

REM # Find the product ID's under [HKEY_CLASSES_ROOT\Installer\Products\....], search for keys containing groupwise
REM # ID's GroupWise version 703
REM # {0555184D-82B5-4DA9-95E2-8BF821C95337}  - Groupwise 7.0.3 
REM # {328C3AB0-0506-46C2-83BF-B517F4FF8D7F}  - v8-Groupwise 7.0.3
REM # GroupWise version 701
REM # {B9A93A85-1997-4381-8979-4B0BB28AEBC7}  - Groupwise 7.0.1 

echo.  Removing GroupWise related services and registry entires...
"\\\gw\SDD\CleanIt\cleanit.exe" /sn /rws
REM # Cleanit removes remainder registry entries and Windows Messaging components
REM #  /sn = silent - /rws = also remove MS Webservice components 

REM # Manual directory cleanup C:\Novell\Groupwise if needed
rmdir /Q /S %systemdrive%:\Novell\Groupwise

REM # Reboot here!?   Might be cleaner!  Not doing so yet...

REM # Writing %TEMP%\gwlogin.reg and injecting default POA connect settings
echo.Windows Registry Editor Version 5.00 > "%TEMP%\gwlogin.reg"
echo.  >> "%TEMP%\gwlogin.reg"
echo.[HKEY_CURRENT_USER\Software\Novell\GroupWise\Login Parameters] >> "%TEMP%\gwlogin.reg"
echo.[HKEY_CURRENT_USER\Software\Novell\GroupWise\Login Parameters\TCP/IP Address] >> "%TEMP%\gwlogin.reg"
echo.@="" >> "%TEMP%\gwlogin.reg"
echo.[HKEY_CURRENT_USER\Software\Novell\GroupWise\Login Parameters\TCP/IP Port] >> "%TEMP%\gwlogin.reg"
echo.@="1677" >> "%TEMP%\gwlogin.reg"
regedit /s "%TEMP%\gwlogin.reg"

REM # Inject custom Address book colon settings and search sequence
regedit /s "\\\GW\SDD\v801\abook.reg"

REM #Installing GroupWise 8
echo.  GroupWise 8 Client is being installed, please wait...
REM # Installing the GroupWise 8.0.1 Client using custom values listed in setup.cfg  and setup.ini

REM # NOTE!!  By default GroupWise 8 will be installed in C:\Program Files\...
REM # Create or modify NAL Apps for GroupWise & Notify accordingly