I don't think any dreamcast emu would be released even till a year after xbox 2 comes out. With an emu, I mean an emu that runs commercial games. BTW, dreamcast is a console of the same generation to which Xbox belongs, isn't it? And how would you run DC GDs?
I am sick of people who tell us that, instead of searching for an emu, get the console. I need to tell such people that, usually, people ask for emus only because they are tempted by the prospect of playing quality games for free. It doesnt matter if the console is a DC, GC, PS2, 2600, NES or even the Xbox. Its important to note that they wont even toy with the idea of buying such games/consoles in real life...