the whole process would be easier if you had nero, as it has a special tool for burning .iso images to dvd's. of course that costs money, and the only way to get it for free would be to obtain it although illegaly, quite easily. i mean one could just go to a website such as www.crackspider.net
and get it off their for free quite easily. of course thats illegal, and i highly reccomend against it. in fact i strongly urge you not to do that.
what happens if you pop in a dvd into your dvd burner, open the dvd's folder up on your computer, drag and drop the .iso in then just hit write file to dvd?