Please I need help!! I cannot find the way to completily uninstall SQL2005!!

I cannot get some useful advise about this, that's why I'm posting again,
removing a SQL 2005 instance shouldn't be that hard!!!

My problem: I've installed a SQL 2005 Enterprise default instance
side-by-side with a
SQL2000 named instance.

Then my SQL2005 instance became corrupt and I've decided to uninstall, but
it seems that there's no way to completily remove the instance.

My first attempt, was removing everything that refeers to SQL2005
Enterprise using the Add/Remove Programs option, I've also used the
Microsoft Clean UP Util.
I've noticed that the uninstallation process does not remove all file-system
folders, but I haven't removed the manually.

On my SQL Server Service Manager I still can see both the SQL2000 and
SQL2005 instance, if I select the SQL2005 instance I get the following
error:
"The specified service does not exist as an installed service."
wich tells me that the service is not running.

When I begin a new SQL2005 setup, on the installation wizard, on the
instance name form when I click on "Installed Instances" only my SQL2000
instance is listed. So I choose to install SQL2005 as a default instance.

When the setup progress tries to validate instance name I get the following
error:
"An instance with the same name is already installed on this computer. To
proceed with SQL Server Setup, provide a unique instance name."

I need to fix this without formatting the server. That´s not an option to
me, there has to be a way.

Thanks a Lot!
Beto