Reusable website template

I am looking for a template I can use for the websites of a number of small clients all in the same line of business. I need to keep the cost of creating each website as low as possible.

It must be possible to change the colours and the images on the template so they each look different. I am comfortable using CSS.

The template should be fairly simple, clean and modern looking and should not use Flash.
There needs to be a home page and one other page which can be used for any purpose (e.g. about us, contact us etc.)

Menus should be automatically generated as each site will have a different number of pages with different content.