i am thinking about getting one for my nikon d50...

;)

Well, I don't know anything about Nikon, but I have the canon rebel xt and the speedlite 430 Ex. I am very happy with it. It connects to the camera, and adjusts the flash level for focal length and apereture and shutter speed. Pretty simple.

DOn't know how much that helps with the difference in cameras though...

Julie -- I've heard good things about the SB 600. The SB 800 is awesome, but you can do a lot with the 600 and it's cheaper.

I have the sb800 and love it! The sb600 is a great choice if you're on a buget.