I finally got the Tumi adapter. $85 on ebay! What a bargain! This thing is fantastic! It uses the same tips as the Kensington adaptor, but is much nicer IMHO. It comes with retractable cords, air & car adapters, and many tips, including the new Dell N19. The carrying case is very nice and compact.

I highly recommend this adapter. It's a steep $195 retail, but maybe you can get lucky on ebay like I did.