Hee hee - Sara!
I use my laptop at work, and it has a built in microphone which works well.
However I do have a headset, that has microphone that is attached to it, and that is fantastic!!!
stand alone Microphones are not that expensive for the PC, but with a headset, you can chat without waking anyone, and also hear much better. They simply plug into your PC - usually they have 2 connections - one for the headset, and the other for the microphone.
Let us know, I would love to "chat" :D