In case you want to tweak the width of IGoogle's columns, this Greasemonkey script is pretty good. It's easy to adjust the width of the columns in each tab, but the settings are only saved locally. That means you'll see the customized columns only if you use the same browser on the same computer. Maybe a column resizing gadget would be a better idea.
To install it, you need Greasemonkey for Firefox.
Note: If you use a localized version of Google, after installing the script, go to Tools/ Greasemonkey/ Manage user scripts, select "Google Homepage Resizeable Column" and click "Edit". Replace "http://www.google.com/ig?hl=en" with "http://www.google.*/ig*" (remove the quotes).