Inside the headlight on the low beam there is a little metal thing. like a wire cylinder. What is it and do I need it?

That ring is designed to allow the light to be cast on the reflector assembly in the right manner. Without it, you won't project light far enough or concentrated enough to be seen. Your lights may also appear to be aimed incorrectly.

iight... thanx will. I just got my new HID bulbs today, and I took those things out now i have to put them back on. lol. Thanks for the help man.

You bet. Just think of it as a 'director' to make sure the lamp illuminates on the right part of the reflector assembly. Both pieces work hand-in-hand.

if that'* tru, why do I not have one in my new headlight? hmm... perhaps it'* already been aimed w/o that thing?

our newer gm cars have those aimer doo dads in them and i can really tell the difference between them and the headlights on my ford, which doesnt have 'em. much brighter and better forward projection of light

Different style of lights bud.

If you bought the light new, I'd bet the reflector assembly was redesigned to work without it.