Update: The setup will prompt you for product key. You cannot find any way to get it on the download page. You need to obtain it at Windows Vista GetReady. If you registered for the Customer Preview Program with the release of Windows Vista Beta 2 in June, you do not need to register again. Just use the product key for Beta 2.
So, you are eager to download and try out the Windows Vista RC2 over the weekend? After getting through the time to download the 2.49GB ISO image, you need a tool to open it if you want to take a look at what is included inside. A search in Wikipedia quickly reveals the ways to handle ISO image.
Most operating systems (including Mac OS, BSD, Linux, and Windows with Microsoft Virtual CD-ROM panel) allow these images to be mounted as if they were physical disks, making them somewhat useful as a universal archive format. For Windows user, you can just download Microsoft Virtual CD-ROM Panel to do the job. Yes, you don’t need a shareware or open-source utility. It is free without asking the authenticity of your Windows XP copy.