I've only recently started using emulators and so far have only seen .RAR files, but I just downloaded Sakura Taisen disk 1 for the Dreamcast and it didn't use any .RAR files.
There is a .GDI file, two .BIN files, and a .RAW file and I'm not sure how to use them. Any help would be appreciated.
Also if it helps, I'm using the Null-DC emulator