Downloaded an ISO/ MDF image(NO, NOT A PHOTO)? Dunno what to do with it?

What you're facing is a very trivial problem. The ISO / MDF are proprietary image formats. That is, these files have many files within them. The structure of the file is a replica of the CD / DVD that was used. As a result, you now have a complete dump of a CD / DVD in your Hard disk. Now, you have 2 options :

1. Burn the CD / DVD image onto a disc :

You can do this by using NERO or any other disc writing software. Simply select "Burn Image to disc" from the NERO menu and select the image you have. The image will be burnt onto a CD (image size < 700 MB) or to a DVD (image size >700 MB). This can be done if the image format is ISO. If it is in MDF format, you have to use Alcohol 120 % instead. The UI in A 120% is very neat, so you should have no trouble doing it.

2. Mount the CD / DVD image onto a Virtual Drive :

A virtual drive is a FAKE drive that is created by a software such as DEMON TOOLS(www.daemon-tools.cc/) or Alcohol 120%. The image you have, can be "mounted" onto such a fake drive, which is also called a "Virtual Drive". This means the software tells the OS that a CD / DVD is present physically even though it isn't. This is pretty useful, if you do not have a CD / DVD drive at all! Once you have "mounted" the disc onto a virtual drive, it should be available in your "My Computer" as a CD / DVD drives' icon. These images auto play, like any other CD / DVD ROM and thus you can disable this action too.

Some image files require other software. The image files in the format DAA require Disc Juggler. So, be sure to "Google" the image format in order to know, which software you need in order to get it working.