I know I'll be the dissenting opinion. But after having a MX900 (part of the DiNovo package I had) for 2 weeks, I decided to try the Microsoft Optical Desktop Pro v2 (I really wanted to keep my natural ergo keyboard).
The v2 of the MS wireless mice are nice. VERY smooth and VERY responsive. They feel better in my hand than did the MX900. It doesn't have a recharging base but you can use NiMH if you want and it doesn't take that long to change the batteries. Also, MS is claiming 3-6 month battery life for the v2 products. Hell, I'd be happy with 2 months inbetween charged batteries...
Overall, I think they did it right!!! If you are looking for the straight keyboard variant of it (not the Natural), it is the MS Optical Desktop Elite.
Drivers seem to work better than Logitechs too...