I have come to find that using UDF or ISO files are quite easy to mount with the right programs. First of all, if you come across a UDF file in a download, no problem... Use MagicISO to deal with this type of file. It is a free downloaded program, unless you would like to pay for it but, it's free none-the-less.
The ISO type files are a little more easier for me to deal with. I use Nero 10 to mount the disk images to a dvd. I found that Nero 10 is the most easiest to use out of all the other programs I have tried, a little pricey but, easy. Once you have the ISO file, just create a DVD (ISO Image) with Nero. 1-2 hours later, you have your mounted disk and it should work just like buying the real thing from the store.
Please contact me with any questions to this or post below.