The Sony Vaio VPCCW17FX uses the Realteck ALC262 codec and out of the box Ubuntu 9.10 the internal microphone does not work.  However the mic input jack does work.

$ cat /proc/asound/card0/codec#* | grep Codec
Codec: Realtek ALC262
Researching on the web there were a lot of folks across a lot of distrubtions having issues with this codec with ALSA & Pulseaudio.  Now I’m not a fan of Pulse Audio but I did get this to work without switching off Pulse.
As admin edited/etc/modprobe.d/alsa-base.conf to add the following line at the end :
options snd-hda-intel model=auto
Reboot and bring up your audio recorder to test!