The freeware utility from Microsoft to mount ISO Images doesn't work in Windows Vista. Thankfully there's another utility that does.
The utility that we will use is called Virtual Clone Drive. This utility will let you mount .ISO, .CCD, .DVD, .IMG, .UDF and .BIN files. Download the utility and start the setup process.
Select Yes or OK at the hardware prompt and continue. You might have to restart your computer. Now you should be able to mount any ISO image by just double-clicking on the file. Note: If you are going to reinstall this utility, make sure you uninstall it first, or you'll BSOD yourself repeatedly.
This utility does not work on Windows Vista 64 bit edition.