Generally, ovulation would come before AF, so certainly you can conceive. I don't see why carrying the baby to full term would be any different than with any other pregnancy, except if your pregnancies were really close (time-wise), then that might be harder on your body.
Monica, I have a friend who conceived their second child that way. She hadn't gotten her first ppaf, but was convinced she was going to ovulate soon. They charted for a few months and she got pregnant. At her first ob appointment, when asked how long since her last AF, it was something like 34 months! They couldn't believe it.
Thanks for the answers everyone- I appreciate it! I'll keep you posted-- it is too early for me to test but I have been preggers twice and feel it again. I am afraid to get too excited but how can you not? I can't take a test until Friday.