Chankast requires what are known as self-booting disk rips. The rips that can be found on the net are either self-booting or require a boot disk. Sometimes, the info on the disk, such as videos and music, has been either removed or downsampled so that all of the game data can fit on a standard CDR.
Like others here, I'd advise you to just seek out a Dreamcast system. If you're going to take the time to pirate a Dreamcast rip, you might as well just burn it off and play it on the real thing. It's worth it for the other emulation options it offers anyway. As a NES kid, I missed out on the Sega Master System. However, the SMS emus that are out there rock beyond belief. Stay away from the Super NES emus though. Ugh...