Gazza,
Try this site
http://code.google.com/p/gimp-dds/
I was wrong it wasn't an executable, but its very ease to locate it in the proper place.
Just open the zip and there is a read me with directions to the location. I am using 2.8 and 64 bit check to make sure you get the right version for your system.
Good Luck.. Sorry it took so long to get back to you things are getting crazy with the holidays coming up
If you still have problems go to the GIMP plug in registry
http://registry.gimp.org/
Any questions I may be able to help, Its not strait forward when saving you need to export then in the lower left there is a blue text string that you click on to select .dds then it takes you to the next screen.
Seahorse/John