I wanted to create an .ISO image from one of my Windows XP CD-ROMs. Unfortunately, I could not find such a feature in Roxio, which came pre-installed on my old Dell laptop. After some searches I ran into the free IsoRecorder, which solved my problem. Once IsoRecorder is installed, you can create an .ISO image just inserting your CD-ROM, right-click and choose "Create image from CD":
Please note, IsoRecorder did not prompt me to restart my machine, which I had to do to get it working.