Systems Management

are about to reconfigure all GPO settings and wanted to know what

This seems to have been out there for a while - hopefully this is not too late:

Computer COnfiguration > Administrative Templates > Windows Components > Windows Installer
Setting State
Disable Windows Installer
Always install with elevated privileges
Prohibit rollback
Remove browse dialog box for new source
Prohibit patching
Disable IE security prompt for Windows Installer scripts
Enable user control over installs
Enable user to browse for source while elevated
Enable user to use media source while elevated
Enable user to patch elevated products
Allow admin to install from Terminal Services session
Cache transforms in secure location on workstation
Logging
Prohibit User Installs
Turn off creation of System Restore Checkpoints
Prohibit removal of updates
Enforce upgrade component rule
Prohibit non-administrators from applying vendor signed updates
Baseline file cache maximum size
User COnfiguration > Administrative Templates > Windows Components > Windows Installer
Setting State
Always install with elevated privileges
Search order
Prohibit rollback
Prevent removable media source for any install