How to create an ISO from files?

OK I have just gotten a DVD burner. I would like to burn a few dual layer dvds but I don't want to learn on them. I'd like to put some videos on the dual layer disk but I want to create an ISO file for them first so that I can load it up in a virtual dvd drive to see how everything works before I burn.

What programs do this?

::edit::

If it were somehow possible to burn to file or somthing like that.

use a program like nero, correct a "project" and just save it as an Iso.

Use Nero 6 or whatever to create a new compilation, but save the file to "image recorder" and then save as .iso somewhere on disk when prompted.