CSS3 has some neat column layout options, but they're not very good compatability-wise, and a fair number of the options aren't supported by a large number of browsers.
If you're seeking to make columns of variable/fixed width, then this is probably the article you're looking for:
http://www.alistapart.com/articles/holygrail
Using this method, you can set one or more divs to a fixed width, while having another resize appropriately to fill the page.
If you just want all your columns to resize, then just make them all float: left
, and width: {percentage of page}%