I was born in 79, and have always been aware of the show as a kid, but never watched it. Pop culture being what it is, I knew about the premise, the Doctor, the TARDIS, the Daleks etc, but had never truly watched the show. From reading old Starbursts and TV Zone's, I built up a decent understanding of the backstory, and all that, but it wasn't until the Paul McGann TV movie that I actually saw an episode - and I enjoyed the hell out of it. Were there plotholes you could fly a starship through? Hell yeah. DId the Daleks sound like they were on Helium? Absolutely. But I loved it.
Albeait, not enough to go back and watch the older ones. At the time I loved the slick production values, the paciness of it, and trying to rewatch the older ones just seemed like a step backwards to me.
So, come 2005, and I watch the new series, and it sucked me right in. Great production, great writing, Ecceleston was excellent, as was Tennant, and now Smith. Watched them all, and loved it. Couple of duff episodes here and there, but I still never miss it. Total New Who fan.
I never did go back and properly watch the Classic show. A friend of mine sat me through The Five Doctors, and Genesis of the Daleks. I enjoyed them, but I'm not inclined to rewatch the older ones, although I've a massive respect for them as they inform the new series. But McGann, Ecceleston, Tennant and Smith... they're my Doctors.