Here are a couple freeware ISO mounting programs that I've used. In general, I like powerISO. Their free version opens with a timed pop up window asking users to register. You can click out of the window by clicking the X in the upper righthand corner. Check out my article on using powerISO to mount an ISO file.
powerISO works with Windows 7 and 8.
NOTE: powerISO recently added size limitations to the ISO creation tool. This means that unregistered users must use a different tool for larger sized ISO creations. In which case, I like to use: IMGburn.
Guide: Create ISO Images