I've been around Buddhist teachings for years; the truths about the transient and selfless nature of reality and how the mind creates suffering due to ignorance of reality and cravings based on that ignorance... it spoke to me. I took up meditation (sometimes) and continued to study, and eventually become a moderator on a Buddhist forum that was open to people of all traditions (and none), which gave me plenty of variance in individual perspectives on what the Buddha taught. I didn't believe in the metaphysical or supernatural claims of these sects (I'm a Skeptic before all else), but found it a useful methodology for overcoming the deepest fundamental delusions (i.e. the delusion of "self"). Simple teachers like Ajahn Chah put it plainly, Zen showed its original face, and later I read Stephen Batchelor and eventually Eckhart Tolle. Let's not even talk about the time I spent on Deepak Chopra, who is really teaching something else. =P
Still, I never actually called myself a Buddhist. Since "atheist" says almost nothing about what I do believe and sets people on edge to begin with, I think "Buddhist" will soften them up... and when I tell them that I don't believe in any gods, they'll be more receptive. Buddhists are much less of a threat in the eyes of believers. It'll be an experiment for me, since my beliefs haven't changed in any way, to see how people react.