Smart Boot Manager can be run from a floppy disk without ever installing it to the MBR (from a floppy is the way that I would recomend using it if you wanted to find out if you liked it). Still, I've had no problems installing it to an MBR or removing it, although I like XOSL much better. I didn't mention XOSL in this case because XOSL must be installed; it can not run from a floppy.