I have both the cordless keyboard and mouse from Logitech. The mouse died on me after 5 months and the cursor was going all over the place, tracking on the desktop is becoming impossible and even though the rollers and balls are clean. I got it RMA'd but after a couple months I couldn't take it anymore after I tried the MS optical mice, the tracking was just so much better.
However the wireless keyboard works perfectly, the multimedia buttons are very very useful and it's exactly as advertised, "keyboard without wires".
aznmist,
Infrared requires line of sight. RF (which is what Logitech uses) is not line of sight and has a pretty decent range, not that you can even see your monitor at the maximum range.