Best adapter for Nikon and screw mount lenses (M42)

I'm quite happy using an inexpensive adapter, the type with the corrective lens to allow for infinity focus, on my D40 & D80. I've had some real "dog" M42 lenses, but some that are totally sweet. This is a shot using a 135mm f2.8 Aetna-Coligon M42 mount lens. Not bad at all, and fun to use. This one has 13 aperture blades, making for razor-thin depth of field, and smooth OOF even at F8. 8-)for