Hi Colleen, and welcome to the site (officially now that you're posting)!! It's so nice to meet you, and we look forward to many posts from you in the future.
Congrats on your marys and HIM- and an even bigger congrats on signing up for IMAZ 08!!!! Denise, Laura and many others can tell you all about the course and what to expect!
As for programs, for the IM I did I used Trifuel. I LOVED it!!! It was so clear cut as to what I was doing every day- it took all the guesswork out of what to do at the diff. stages of the preparation. Also, the weekly hours weren't that intense. The longest week was 19 hours (and that was 5 weeks out from the race). The program assumed that I was faster than I was, so I just added a little extra time to each workout to compensate. It was my first season of tris and within 7 months I had done my first tri and then an IM. It was a fantastic program (but I know there are soooo many other good ones out there). Bonus- it was free and easily accessible- both good for me.

Anyway- best of luck in your upcoming tri season!! Glad to meet you!!!