Logitech Cordless Desktop MX 5500 Revolution Keyboard & Mouse

I bought this because my Logitech 5000 mouse/kb combo developed problems... switch-bounce on the mouse meant I often got double-clicks instead of singles and the kb kept losing its connection. The mouse had seen some punishment over the years, so it was to be expected, as no switch lasts forever. So, I had to bite the bullet.
I didn't bother with the cd out of the box, as I'd read a review elsewhere which advised downloading the latest software for Windows 7 instead. This seamlessly uninstalled the older version for the old combo and found the new equipment straight away. Nicely done.
The keyboard is much more solid than the older one, with a crisp, positive feel to the keystrokes - key "clatter" and noise is vastly reduced as well. The display is clearer and I like the FN button to get at the extra functions - a neater solution to that used on the 5000. I miss the volume and zoom sliders that the 5000 had, though, but it's no biggy.
The mouse is outstanding - much more ergonomic than the old one, the ability to spin through a document rapidly is excellent. It took a while before the scroll wheel would spin freely (a couple of hours) and then it was a breeze. I love the ability to flip through the active programs with the thumb wheel - very neat. In addition, the ability to set the various buttons/wheels to different functions for different programs is brilliant. All the buttons have a positive, crisp feel without requiring undue effort. Tracking is pixel-perfect on all the surfaces I've tried out. My only criticism of the mouse is the button behind the universal scroll-wheel... it's a little awkward to get your finger to easily, and I miss the buttons each end of it (as I had on the 5000). It's a small price to pay, though, for the increased functionality elsewhere, and I very quickly got used to the new "feel" of this mouse.
This is not solely a "gamers product", as a previous reviewer stated - I don't play games (any more) and I'm loving it.
In sum, a much better engineered product than its predecessor, well thought out and worth every penny. You might not like mice/keyboards with lots of bells and whistles... but, if you do, then I think you'd be hard-pressed to find a better combo at this price-point.