Pseudo re-install on windows

Hi,

I am trying to find a way to re run the PostgreSQL 8.2 installer on a
windows XP box without uninstalling PostgreSQL. The reason I'm doing
this is that I'm testing out an installer that embeds the PostgreSQL
installer (as a msiexec silent install) and I want the existing
installation files to stay where they are so I can activate the
PostgreSQLservice back on as if nothing happened should the wrapper
installer fail.

What I'm doing is try to fool the installer by deleting all registry
keys that pertain to PostgreSQL (PostgreSQL itself, but also things like
PgAdminIII). With a "clean" registry, the GUI installer (which I'm
testing thinking it should behave like the silent installer as far as
detecting an existing installation is concerned) still detects
PostgreSQL is installed and offers either repair or remove. I'd like to
reinstall everything in another directory altogether so what's left to
remove in my system so that the installer doesn't detect an existing
installation ?

Also, I'm reinstalling with another PG serviceaccoutn and superuser.
The first time around, I let the installer create the default postgres
accounts but this time I want to use another account name. But the GUI
installer does not give me the opportunity to specify another user so
maybe checking for an existing postgres account is how the installer
knows there's an installation ? Even for the msiexec silent installer ?

Thanx for pointers,

Yves Moisan