RC0 of Windows Server 2008 was made available earlier this week. I am currently installing it inside a Virtual PC and I have to say I'm impressed so far. The installation process is much faster and smoother. Also, it is very strange to see how far the "secure as default" mantra of Microsoft has come over the past few years. In Window Server 2008 when you first install even the Sound Service is disabled and you have to enable it before sounds will come out of your soundcard (this is made easy by some nice UI from the standard volume control). How times have changed...
BTW, when installing Windows Server 2008 inside Microsoft Virtual PC 2007 I said that it should use the Windows Vista soundcard when creating the initial VPC configuration and it seems to work great.
I'm pretty sure the sound service being disabled by default is not new to Sever 2008 as it was the same for 2003.