Personally I own a wireless keyboard (
Adesso WKB-4000US) which I am very satisfied of. I never had to charge the batteries (AAA) since I got it (6 months). And it works either on Windows XP or Linux without any drivers to install. The range of the keyboard is good and that's fine for my usage. Also, the manufacturer says that it works up to 100 feet. But obviously it's not 100 feet through any walls or floors. So, I guess that could work for you but I don't know much what you really mean by "...in an other room..."
Otherwise, I found that my laptop is a very good alternative. I just hop on my server through VNC and I control it with my laptop. And this works from a further distance since my wireless network has a very good range.