We co-sleep with Morgan, and have since she was born. It started because she simply would not stay asleep if she wasn't being held or touched-we tried the double swaddle, we tried everything, and it just didn't help. So if I hadn't brought her to bed (she was and still is breastfed, although she only nurses at night now) I never would have slept.
But yes, the number of co-sleeping death is far less than SIDS, and there's a lot of research that shows that having Mommy breathing so close helps regulate baby's breathing. (Also, it seems a lot of those deaths relate to drunk or drugged parents, waterbeds, or other siblings causing the problem.)
I sleep on my side with her head on my upper arm, so it's physically imossible for me to roll over on her-plus you'll be surprised how AWARE you are of your baby!
A good book to get is the Sears' Baby Sleep Book. They are strong co-sleeping advocates but not in a pushy way, and offer help for all parents no matter what "sleep method" they choose-lots of practical advice!