I've never had achilles problems myself (knock on wood) but it's something that plagues a lot of runners (not usually complete rupture though).

Check out running sources for more info. Tim Noakes (MD) "Lore of Running" has 7 pages on the topic, including a discussion of the surgery you're about to undergo. Success rate for the surgery is quite high, but rehab takes a l-o-o-o-o-ng time. You already know that.

Good luck!