PostgreSQL uninstall fails

I have to do a lot of testing which involves uninstalling PostgreSQL
completely sometimes, but there is a lot of crud still left around after
an uninstall.

1) the installation directory with PostgreSQL droppings - I have to go
manually remove it. I do not know why the uninstaller does not blow it
away.

2) Registry Keys - dozens and dozens of keys that confuse the next
installation
- to test: Install 9.0.1 then uninstall
- Install 8.4.2 and launch pgadmin III and you will see what I mean

I do a search on every key that contains the word 'postgres' and have to
delete that manually

3) The postgres user remains on the system

Can anyone get me started on where to checkout the postgreSQL installer
code and fix it so that it is no longer broken? I may need to ask a few
questions so if I can be put in touch with the uninstaller team, would
really like to get this fixed and go back and patch everything from 8.4
forwards so that it is fixed.

It is very time consuming for me to do 1..3 and I am sure others as well
and I want to get this fixed as soon as I can.

Regards,

J.V.