Removing Downloaded Program Files on Vista
Don't be silly, by trying to go through the registry to delete these entries, clearing the registry, doesn't actually remove the binaries on the computer.
To remove the "Downloaded Program Files" you should run IE and do the following:
1. Choose the Tools menu
2. Select Manage Add-ons
3. Select 'Enable or Disable Add-ons..'
4. Look for the download program you want to remove, change the selection by going through the drop down list.
5. Once you find that program, highlight it, and on the bottom right section, click 'Delete'
That should be it.
All the best.