How to detect a "RadioButton" server control 's "Checked" property on the client side?

[bredal Jensen]

Dear gurus,

I have a "farm " of radio buttons server control in a table. I need to
detect
when the user has selected any of them( before any postback).

i'm not quit sure how to do this.
Is there a way of making the readio button trigger a post back to the server
whenever it is selcted?

Many thanks in advance..