Doug,
I'm not a web designer "pro" -- but as a business owner, I needed to learn as much as I could over the years... one thing I AM is a web consumer and I buy almost everything in life online - from groceries (freshdirect.com) to electronics -- and as a consumer, I know what kind of stores I like, and what store experiences are easy...
If all the big boys do it one way, there may be something to learn from them. Granted, Amazon.com's checkout may be a bit extreme (ever try to add something to your cart once you've started checkout on amazon? it's not easy!) -- however, if you visit the top-ten sites in your space, you can learn something.
My primary screen right now is a 17" laptop 1680x1050 - but I also have a Dell 30" in my studio and also have a bunch of 1024x768 screens -- my wife's laptop is 1152x768. If a page doesn't put the good stuff into the top 90% of a 1024x768, I probably can't expect the user to scroll. What would Jakob Nielsen say on this?
http://www.useit.com/alertbox/screen_resolution.html