Geektool won't open geeklets?

I've tried downloading geektoal and have managed to set up a couple of basic ones on my own but whenever I try and download and open a geeklet it comes up with this message.

The document “Time1.glet” could not be opened. GeekTool cannot open files of this type

Also, Geektool doesn't display in System Preferences, not sure if that makes a difference?

If anyone can help that would be brilliant, thanks!

If anyone else has this problem, I think it was an error I made in set up. Basically if you select 'Open With' and then go to 'Geektool Helper' then that worked for me