How to select postgres for usage instead postgres-pr?

Hi,
I am using pgRails which came pre-installed with postgres-pr and I now wish to use the native driver called ‘postgres’. I have done the following:

'gem install postgres'

I now have both postgres-0.7.1 and postgres-pr-0.4.0 sitting in C:\pgRails\lib\ruby\gems\1.8\gems

What do I need to alter in my database.yml/postgresql_adapter.rb documents so that I can access the postgres driver?

Hi,
further to my additional email the gem build for postgres did not work, so I downloaded and copied postgres.so into:

C:\pgRails\lib\ruby\site_ruby\1.8\i386-msvcrt

Again, how do I point rails to using this driver?