My boss has a sweet setup in his house. He's got a PC with the signal going to each of 4 different widescreen plasma TVs at various locations throughout the house. (Poor guy- he has to make do with only four 49" plasma TVs...

) He wanted a wireless keyboard and mouse to use with it so that he wouldn't have to sit at a desk to work. (Which I have to give him credit for here - if I had a single 49" plasma TV, I sure as hell wouldn't be working!

)
I got him the LogiTech MX Duo, as I've heard good things about it. He's very happy with it, except it only works in one room - it won't work through a door or wall. He wants to be able to use it anywhere in his house and still have it function properly. I was under the impression that these operate on IR signals, meaning line of sight must be maintained for it to work. Is there one on the market that utilize RF signals so he could use it in the general area?
Does anybody have any ideas as to what I should get for him or if something like this even exists? Maybe a way to get the current wireless setup to work over a wider area? (Wasn't sure if this should go here or in buyer guidance.)