Shoutbox

Hi,
I'm trying to redesign my room, but to prevent me from having to move stuff around all the time, I want to re-create my room in a 3D-model first.
I myself thought that Hammer was the best tool for this (as you can easily cut and add pieces to it), however it won't work without a game installed...

Would anyone know how to get Hammer to work without a game?
or a similar 3D model program that doesn't need one?

Thanks,
TB