OK, I tried the extract option. Winzip gave me the same message. "The parameter is incorrect.". It's not an actual disc. It's an image. I tried burning it but when I put it in CD players, still no audio and I tried moving the .CDA files off the disc I made from the image and it still gave me the "The parameter is incorrect." message.
I wish I had the real Radiant Silvergun game though. You try getting it on eBay, if you can manage to find a copy, it goes for like $150+
edit: I think something is wrong with the emulation world. They have the skill to make a Dreamcast emulator that can run Ikaruga with almost 100% compatibility, yet they can't make a decent Sega Saturn emulator.