Let's make everyone happy here. Setting a max-width on .wrap at 960px, so now the page fits on a 800x600 screen, but doesn't get overly-wide on a high-res screen.
Changes to .submitbox necessary as a result, now floated instead of positioned absolute; new containing div around main Post page column to keep it from overlapping submitbox.
Also set a max-width and word-wrap on the .comment column on the Comments page; this keeps overly-long words from breaking layout (for the one browser that supports it currently, anyway).