Regarding the Adesso WKB-4000US, I have a keysonic ACK 540RF that looks and acts exactly as the Adesso device.
Tested and working with Mythbuntu 8.10. And the price is a little lower at about £26 GBP (British pounds)
I have been using this keyboard for over a year and my biggest complaint with it is battery life. The keyboard is used with our media center(computer, tv and stereo all operated via media center and this keyboard) and it's often in use from 10 a.m. to 1 a.m.; with that amount of keyboard usage, I'm required to recharge my batteries every two days. Also there's no indicator that the batteries are starting to run low, we now know that when the cursor starts to get stuck (barely responsive) then it's time to recharge. I found this site because I'm desperately seeking a new keyboard. When I saw the comment that said the Trust has a good battery life I felt the need to let you know my experience with it. It's not bad but if it's used as much as my family uses ours then the batteries most likely won't last. We use rechargeables because regular batteries were running out every 5 days and that can get costly.