Chicks are tough little beasties. They don't need a heat lamp over their entire brooder, just a place where they can go to warm up if necessary and a place that's out of the wind. It doesn't even have to be a specific temperature (like 95 degrees the first week, 90 the second, stepping down) if you look at how the chicks behave. If the all huddle under the light, lower the light. If they all fall asleep in a circle around the edges of the light, raise the light. If they are sort of evenly scattered all over the brooder, everything is fine.
I used to do the stepped-down temperature thing, but then I saw how my broodies handled chicks and talked to some old-timers, and now I'm a lot more relaxed.