I've not used any BT keyboards recently, so I can't recommend a particular one - it may be worth heading out to a PC store and giving a few a try, as it's good to get a feel of one before purchasing.
Bluetooth keyboards aren't 100% secure - so it would technically be possible to intercept... but it would be more secure than some wireless keyboards. AFAIK, BT uses some form of 128-bit encryption - there's more mentioned on this Wikipedia article:
I did some googling on the logitech wireless keyboard range and it looks like they use 128-bit AES for the 2.4Ghz wireless range. Assuming that it's been implemented correctly, that should provide protection from casual hacking.
Personally, I'd be happy with either - but would probably go for Bluetooth for convenience. The range is pretty limited, so that also limits who could have access.
Thanks Ian, lot of good info.
I was interested in the Microsoft 6000 Bluetooth keyboard for my desktop, but some of the stuff I've read gave me the impression it would be like grabbing a tiger by the tail. LOL
Not because of that model, but because of Bluetooth complications. Not sure it'd be worth the trouble.