SQL 2005 sp2 wont reinstall on Vista

Hi,

I'm running SQL 2005 sp2 Developer Ed. on my Vista. I had some problems and
I wanted to reinstall it. So, I desinstalled everything from SQL cleanly
using control panel and reinstalled: SQL Server setups tells me that the
Notification Services, Integration Services and Workstation components are
still present and in a more recent version. When I do continue, even the SQL
server service will not install in the default instance, claiming that it
already exists! But there are no SQL server services anymore, and I have even
deleted the folders. Should I start registry cleaning? There are a lot of SQL
components in the GAC, but Vista keeps denying me the right to delete them.
Any ideas anybody?

Thanks,
Jan