Webcam advice /deal

Hi been looking at webcams on amazon and I am just confused by the reviews saw my son today on his as he left for uni yesterday dont know which one he has but want to install one myself so that I can speak to him through msn.

I am running vista and have seen on some reviews even microsoft ones not working with vista, dont want to waste my money on one that wont work. Has to be less than £20 tbh cheaper the better as I am on a budget so the best picture quality with built in decent mic for less than £20 what do you reccomend