Hi,
I recently bought a Dell Vostro 1400 and thought I'd let you know my experiences with Alsa:
I use Kubuntu Gutsy distribution as a base, but follow kernel at a close pace so I use compiled 2.6.24. This didn't support the hda-intel as I expected (don't remember exactly, but master/front/pcm/surround were all in the game but not as expected and I couldn't get built-in mic to work, but this may be due to too little testing).
So I decided to google around and found the model=3stack, dell-3stack options and tried those. Still no luck.
Next I dl'ed alsa 1.0.16 and noticed a mail describing a vostro 1400 PCI quirck patch (model dell-bios). So I tried that, but no luck. After that I experimented with all 3stack variants I could find in the code and concluded that dell-3stack is the best. I now have sound, master/front/pcm volume sliders that work but above all: built-in mic (Digital 1) recording (and skype) works!
I don't know if it's of any value: I immediately flashed the standard A06 Bios to A07 when I found the update on the Dell site and can not tell if the dell-bios model worked for the preloaded A06 version bios.
Hope this helps. If there's anything else I can provide I'd be more than happy to collect the data.
Regards, Martin