If you can not mount iso image in Windows 7, try the utility called Virtual Clone Drive. Virtual CloneDrive can work just like a physical CD/DVD drive and mount .ISO, .DVD, .IMG, .UDF .CCD and .BIN files. Notes that it work on Windows 7 32bit and 64 bit edition.
After finished its installation, you need to restart your computer. Now you can double-clicking on any ISO image file to mount, or right click the Virtusl cd-rom drive to mount an iso image.