Many designers are privileged with fast connections, fast computers, and large monitors. Remember that not all users enjoy the same amenities that you may have. Test the site in different monitor resolutions and on different browsers. Use comment tags to identify sections of your code. It helps to keep your code clean and make modifying your code easier in the future.
Nobody likes to scroll.
If you must put a lot of information on a single page, create a mechanism in which the user can jump between sections. Tables are a powerful tool. You can center an entire page contained within a certain width by using one. Frames are a handy way to aid the user's experience in navigating sites. The drawback is that bookmarks will call only the frame that was marked, not the entire frameset.