Sounds interesting. Which one was it?
Probably
this one at a guess, I don't think Amazon sell it anymore though, but should have something similar.
I have the same one for the media center, except it has a track stick in place of the ball. It works fine for the media tv, but I wouldn't be keen on using it as a working keyboard/mouse.
In general, anything branded with Logitech or Microsoft is of good quality -
ebay gets the best price - the high st shops have a huge mark up on these things eg I have a Microsoft sidewinder gamer keyboard, about £40 on ebay and saw one in hmv for £70.
I prefer the rf receivers to bluetooth or IR. Bluetooth you have to faff around setting up, but with rf it just emulates a keyboard and mouse from the usb dongle. Ok BT give security, depends if you think that's an issue.