2 webcams, same computer, for recording. Wanting to switch between.

I'm wanting to have one in one room of my business, and one in the other. Just extend the usb cables from the computer in the office. Then hit a button to switch between recording one room, or the other (in wmv, avi, mpeg, or something). I figure it's cheaper than security cameras, and I only need 2. What software would I need? Thanks for any info.