Chankast picture problem...

Sounds like you have an integrated graphics chip, most likely manufactured by Intel. If this is the case, stop trying to get the emulator working properly; until you get a decent video card, no Dreamcast emulator will work as it is supposed to.

In short: Not an emulator problem.

A Core2Duo with an integrated Intel chip being able to play Blu Ray movies versus being able to display graphics in a Dreamcast emulator is hardly the same thing. Poor graphics hardware's faults most often come to light in PC games and emulators, because those are the things that tax and use the features of the graphics hardware the most - and this is where most Intel's offerings spectacularly fail.

Basically, any video card released post 2003-2004 will do. Hell, my Radeon 9800 Pro does things fine - you don't need to particularly efficient card, just stay away from Intel's integrated chips. Even ATi's and Nvidia's integrated chips are far better that Intel's.

You can't just simply replace the graphics chip on a laptop; because it is integrated, that means that the chip is permanently soldered to the motherboard. Sure, you could unsolder it, but I don't think you have the necessary training and skill to do something like that, nor will I ever urge anyone to try something like that. There are some laptop models that allow you to swap the graphics chip, but AFAIK, those kinds of laptops are quite rare and expensive.

Note that I assumed in my first post that you were talking about your desktop computer, or at least you'd have a desktop computer handy. If you don't have a desktop computer, you should definitely get one. At least then you'd have the luxury to pick out and swap the parts as you please.

Other DC emulators work equally poorly with Intel's chips (Although Demul let's you choose between OpenGL and DirectX graphics plugins, but I wouldn't hold my breath about those working any better). No, there are no DC emulators for Mac, at least I have not heard of any. Well, you could always get an Intel Mac and run Windows on it, but that's stretching it.

You could always install Darwine and use nullDC with it (yes it does work) on your Intel Mac, assuming you don't have an integrated Intel video chipset on it (and many new Macs do)