DEmul emulates games not just for Dreamcast, but also for the Atomiswave and NAOMI systems. However you do need a Dreamcast BIOS to use it, and this is not included with the emulator.
For now, DEmul can perfectly emulate over one hundred games including: Marvel VS. Capcom, Crazy Taxi, King of Fighters, Sega GT, Sonic Adventure, Star Wars Demolition, Virtua Fighter 3 and Virtua Tennis 2.
For 32-bit versions of Windows. It is possible to find a 64-bit version on the application's website. To see the full list of supported games, click here.