Originally Posted by MikeHopley

Fully fluid layouts, where you define the layout in %, will adapt to screen size but will have distorted proportions and painfully long lines of text at high resolutions.

My preferred method is to use an elastic layout. This is where you define the layout in "ems", a unit of font-size. Combining this with the CSS max-width allows you to keep line lengths constant, while creating a layout that scales up with the text size.

Elastic layouts are rather difficult to get used to, however.