Justin,
hard to answer based on the info provided.
hook-up with an experience web designer (if in the budget) for some content/information architect advice.

simple is best...but not when someone has to scroll ad infinitum to the bottom of a page to get info. it's a delicate balance.
you could employ text jumps if you really did want to keep to one page.

good luck.

Hi Justin. Consolations on your first self help DVD. I'd be curious to learn more about it.

As someone who worked for years in internet marketing companies that sell more or less a single product per website I would say that whoever told you that simple is better was correct. Of course every product deserves a different treatment but here is what I would do if I were you: Make the homepage very simple: Your company/book logo, a navigation bar (about the author, the product, order, contact us), the majority of the page should be divided between attractive graphics that convey your products message, and 2-3 medium paragraphs of texts describing the product. Then two big-ish buttons: "Buy Now" and "Learn more". If the click on learn more they get more information that can help them make the decision.

Hope that helps,
Eylon