microphone issues

so, ever since I installed a fresh copy of windows xp, all my sound settings seem to have gone back to default. I am unable to get a signal on any of the primarily used programs. I do believe that I have everything set the way it should be. and yes, the microphone is connected to the right jack since I have not removed it since the fresh installation.

I tried some tech help forums, but didn't get any decisive feedback either.. I could get some person to upload a video on http://www.youtube.com/watch?v=RPX3dQuEnKo, and a problem occurred. at around 12 seconds you can see the user switching to the recording tab, in which I have nothing displayed. (guessing that there should be either line in or the microphone) I managed to access the microphone tab eventually, though, and it is not muted. (in fact, the mute button is greyed out, but I can still change the volume)

some testing underway, I managed to get a signal while using 0 sensitivity (what could be described as an annoying humming sound). what is more, the person claimed to have heard an echo of his own voice, as well as some sounds from the programs I was running at that time (music, msn chat sounds).

any feedback is welcome, especially from the ones a bit more computer literate. able to post some more in-depth information about my computer and the soundcard if necessary.