Mouser,
I know we're all computer-centric here but I've found using 10x10 lines/inch graph paper is by far the best way to do this (except for complex stuff like laying out a kitchen, unit by unit). Lay out your room on the grid, make some scaled cut-outs for your objects and move them with your fingers.
If your sense of computer deprivation becomes too severe, you can push the objects around with a spare mouse.