Metric Man, I'm new to this thing too! After not riding a road bike for about 20 years, I decided my old knees couldn't take what they used to and biking would be fun. I dusted off my Giant Hybrid and rode about 4 miles on August 3. That went pretty well. Over several weeks, I increased my long ride to about 12 miles while I lusted after real road bikes at several of the LBSs. In late August, I picked up a 2007 Specialized Roubaix.
In September, I worked my long ride up to a bit over 36 miles.
So far, no major issues. I get some numbness in my fingers sometimes, and I'm working on that. If I don't stand up every 10 or 15 minutes, I get some crotch numbness. But my old achy knees are doing great and I'm really enjoying it.
My wife thinks I'm mildly crazy, but she would really think I was if she knew how much time I spend reading various bike forums on the internet during the work day!
Keep riding!
John