From marathon to triathlon to ironman?

Hi all! I'm actually training for my second marathon in May, but since looking for a bike with my wife we have both decided to try a triathlon this year. She is more of a swimmer (and has a decided advantage over me with her longer reach - she's 6'2") and I am more of a runner. Neither of us has gone in for biking till now.

Anyway this site seems to be really great - particularly the training log aspect. I am looking forward to receiving advice!

The goal for my 40th birthday was a marathon (did it!), for my 41st to quit smoking (did it!), and for my 50th one it is an ironman triathlon. Fortunately I have 8 years to get there so it's an Olympic triathlon I am shooting for this year to see if a future ironman is even remotely realistic!!