That speaker mute when headphones are detected works with my Audigy 2 ZS
Platinum Pro.  But it's not done by the Windows mixer.  Rather the Creative
AudioConsole's setting to Mute Speakers When Headphones are attached.

That kind of thing probably needs manufacturer software to work.

It's a whole new Audio concept in Vista.  Even with the updated Creative
drivers for Vista Beta 2 my mixers aren't really behaving properly.  For one
thing, once I close the Audio Properties panel it won't open again until I
reboot.  This wasn't a problem when I used Creative's Audigy 2 ZS drivers for
XP.  But I do get a bunch of new mixers that all slide together at the same
time.  It doesn't seem to jive properly with the volume control though.  This
is hard to explain but it isn't really working properly.  And forget about
configuring anything for recording.

It's nice that my EAX Advanced Parametric EQ and Soundfont Control work
though.  With the XP drivers the EAX worked but only the Microsoft Midi was
working.  It's nicer to use Soundfont's.

WMP 11 still can't give me any audio on DVD's.  Gotta install PowerDVD to
watch DVD's with sound.

I will say that even though the controls are funky, music does sound better
than with any soundcard and WDM combo I've ever used.  I think the audio is
really improved in Vista but it's up to soundcard manufacturer's to work on
getting their drivers and software to work properly with it.