I use a Dremel. They grind the nails and the dogs are absolutely fine with it, they dont move, even the one that was petrified of the clippers. They cost around £30 but you can get other makes much cheaper that do the same job. You buy the circular sanders when they blunt, about £2 for 6, will last for ages.
A quick vid for you to show how relaxed the dog is.
http://smg.photobucket.com/albums/v336/dawnieb/?action=view¤t=Orey_grinder.flv
This is the one I have.
http://www.mtmc.co.uk/product.asp?cookiecheck=yes&P_ID=38788
The replacement pads.
http://www.tooled-