Why do you think people will have browser windows of only the two sizes you mention? Most people I know prefer a browser that's taller than it is wide, like most books. I don't know anyone who uses a browser of anything like the proportions you suggest.
I disagree. You may know a different type of computer user, but the people I know (parents, girlfriend, etc.) view in full-screen. I personally view everything in full screen. I find very few instances that require me to have several windows viewable at the same time. Especially web content. You can't read two things at once anyway (unless you're Tony, it seems).
As for the other suggestions, I don't think he was really asking for something like a code to route people to different locations based on resolutions. I think he was talking about code in a page that will change it's shape based on resolution. Well, my friend, welcome to web design. I'm still dealing with making stuff look better on different sizes.
I tend to make sites that don't go beyond 800 pixels wide. If someone has a resolution of 640x480, I'm sorry, but they're beyond hope and they're probably used to horizontal scrolling anyway. Besides, about 3% of the people out there are in 640x480. Hell, Yahoo's pages are mostly restricted to less then 750px wide (good to factor in the scroll bar).
Frankly, things shouldn't look worse at higher resolutions than they do at lower ones. Unless your eyesight is bad

I'm at 1600x1200 and everything looks fine to me. The fact is that people with higher res screens have to deal with the lowest common denominator.
Of course, there's exceptions to all this, but do what you think looks good. I'm still trying to figure out what that is myself
Oh, and I would talk about Dreamweaver, but I'm pretty much only using Notepad, so I wouldn't be of much help