Ask HN: Incorporating in Ontario - Advice? Recommendations? Experience?

I'm working on a hosted billing app (in a nutshell) that looks like it might see the light of day. Since the application deals with actual cashdollars, I'm thinking a limited corporation makes sense (looks more professional, can't be personally sued, etc.). I've trolled around the internet looking for advice on how to do this, if I should do this, that kind of thing, but it is precious scarce.

Actually, most of the "advice" out there comes from companies offering the service, which doesn't fill me with tremendous confidence.

HN, have any of you incorporated a small business in Ontario or Canada? Why? What issues and pitfalls did you experience? Can I trust these companies whose services cost half as much as the others? Can I trust these companies whose services cost twice as much as the others?

Bonus question: I plan on dealing with Americans as well as Canadians. What challenges does this pose to a Canadian business?