Stay away. There is nothing good that can be done with a Murray. It probably has steel rims so it will suck even as a snow bike. Just wait for it to go in the trash if you really want it. I picked up a similar bike for free and it was so crappy it was a waste of time to pick it up and a waste of space to store it. Plus I bet it has those 26" rims and tiny axles that nobody makes anymore, so converting it may even be impossible.

Although if you do end up picking it up from the garbage, you might want to rotafix a cog on there and make it your joke bike. Whatever you do, don't spend money on parts for it that you can't transfer to a new frame.