Go to the 'sticky' at the top of the css forum and download the Templates tutorial.

This contains everything you need to get you going with a full expanation of what goes where and why. You can then adjust the layout to suit your needs.

It comes as a header, central three column section and a footer. All xhtml and css included.

Info on both fixed and fluid versions.

It works for IE6 & 7, Forefox and Opera and should also be ok in Safari and Konqueror.