I have both a DiNivo and a Micorsoft Wireless 6000.3
I really loved my DiNivo, but 1 of the keys (the tab key) broke off within a few days - which i remapped to another key). then 4 months later 3 other keys stopped working. Logitech is sending another one, however as was traveling there was a gap.
In the interim, i bought a microsoft 6000, and having owned about a half dozen of the higher end microsoft keyboards, i would say this is the best of them. It has a very slight angle in the keys layout, an the keystroke is smaller than other micorosft keyboards which allows for faster and quiter typing. The microsoft has a suppier arrangement of additional feature keys than logitech, except for the really cool volumn slider.
They are both good keyboards, although i would give the nod to logitech in terms of better keys, and the nod to microsoft in terms of better supplimental keys. As i type 10+ hours a day ( a prgrammer), a good keyboard is important and makes a sagnificant performance boost (the best performance boost you can do, assuming a decent box, is a good quality 24inch screen, a nice keyboard, and a logitech mx revolution mouse.