One thing Sam - you make a lot of use of tables. the upside to this is everything stays nice and straight. The downside is something you are seeing - that if the user's resolution is less than you've built the page for,then the number of columns will force scrollbars horizontally.

But the converse - if you went with the least common denominator in size then you will have a lot of empty real estate on the screen for people in higher resolutions.