How do i install an AU plugin?? .dmg file

Hi

I got some plugins to install. I double click the drive.dmg file
and it opens a drive with drive.component in it.
Now when i click this to open, it tells me there is no default application
to open the file.
Can anyone tell me how to install these? What program i need to install them.
Ive installed my camel plugins fine, but these i seem to have a problem with.

Thanks

Andy