Recording straight to iMovie using iSight

Hi all, i've managed in the past to record straight to iMovie using my built in iSight, but i don't seem able to now. I don't remember how i did it & according to some info i read i should have an option next to the little camera/timeline switch in iMovie, but it doesn't seem to be there. Any takers? I'm using iMovie HD vers 5.0.2
Thanks in advance.
Sim

I have iMovie from iLife '06 and it's a newer version than yours but here's a screengrab of where I go to choose my iSight camera.

Thanks, looks like i need iMovie 6 after all. *sigh*