Many of the games and music albums that we download from the Internet are in ISO format (disc images), that can be burnt directly on to a CD without major problems or, on the other hand, can be emulated as if they were being read from an optical disc unit.
Free virtual CD ROM for Windows XP, also known as Free CD Emulator, is a free application, that can help us to create up to 30 virtual units, thanks to which we can emulate any disc image, whether ISO, CDFS, UDF, ROCK or JO. It's a very lightweight application, because it practically doesn't mean any load at all for the system.
The program has a rather dull interface, that only has the buttons that are necessary to create virtual units, and to mount and unmount images, thus being very simple to use.
If you don't want to spend money on an application that can be used to easily virtualize any ISO image, it may be that the best option available is, without a doubt, Free virtual CD ROM for Windows XP.

Only works on Windows XP and Windows 2000.