I recently installed Ubuntu Natty on my Toshiba Satellite A210-139. Everything works fine except the microphone. I can hear a crackling sound also when I record using Sound Recorder, but it's not too bad.
The big issue is with skype, where, besides an annoying, loud white noise, the receiver hears me quite intermittently.
I tried many things. Firstly, I played around with Alsamixer and Pulseaudio with every possible combination. Didn't work.
I also tried what seemed to solve the problem to many users: replacing
load-module module-udev-detect tsched=0
Also this didn't solve the problem.