Problem: It is a very commonly faced problem that microphone does not work, or not detected properly with Microsoft windows viata.
Solution: First of all find the latest version of the audio driver which is compatible to vista, as most of the drivers that are shipped with sound-card or motherboard cd contain drivers which have support for only until windows Xp.
So it is strongly recommended to download the latest audio driver from the internet for your sound-card or on board audio chipset. Install the vista compatible audio driver (sound driver) for your sound-card or motherboard audio. After this re-start your computer. Half of the work is done.
Now plug in the microphone in your sound-card / motherboard audio pin (generally pink in color for microphone).
After this go to control panel > sound and audio device settings. Check whether the microphone is detected by Vista or not. If not, check whether you have selected the frontal microphone or rear, as vista recognizes them separately unlike windows Xp. Correct the configuration of front/rear mic if needed.
The job is done now. Hope this solves your microphone trouble if not please leave a comment.