I'm currently working on improving the emulation of the power vr card to enable support for 3d demos and games. Also the bytecode generator needs a lot more work. Please keep in mind that i'm developing this as a basis for my thesis and there are some things that won't get emulated till i present it (namely the sound core) and i'm not sure if commercial games will boot without it.
That said compatibility with KallistiOS (opensource homebrew OS) applications is already really nice.
Also you'll also need a powerful pc when it reaches the stage to play commercial games. From my tests, with no bytecode generator, a native 64 bit OS makes a big difference. On the same laptop running Vista 32 bits and linux 64 bits the difference is really impressive.
I also plan to introduce multicore optimizations, which will most likely give a nice speed boost on dual core machines which are becoming commonplace
I have tested it on Windows XP (32 | 64), Vista, Linux (32 | 64) but it is being designed to run every where ((lwjgl | java) !=0). There is a binding of a C lib using libcdio so i can access cd rom drives and several isos, and that will be the only non java component of this project.
It will also be possible to use the applet features of lwjgl (i guess people who develop dreamcast homebrew games) will like the ability to place them on a webpage for people to have a look