Well at least you taught me something I didn't know. I have an IBM T40 and didn't even realize it had a built in microphone. Now I do (and it works).

What is difficult to ascertain is whether you are having a hardware problem (microphone itself doesn't work) or a software/internet problem (microphone works but won't signal won't pass through to the internet).

First thing I would do is see if the microphone passes the Test Hardware scenario in Win XP Control Panel:Sounds and Audio Devices:Voice.

If the microphone passes that test (you actually hear your voice echoed through the T30's speakers), you know it is not a hardware or Win XP problem. If it doesn't pass, you know the problem is in one of those two areas.

Either way, I'd attach an external microphone and see if you have any better luck.