How do I specify in HTML or CSS the absolute minimum width of a table cell

Summary

What's the best way to ensure a table cell cannot be less than a certain minimum width.

Example

I want to ensure that all cells in a table are at least 100px wide regards of the width of the tables container. If there is more available space the table cells should fill that space.

Browser compatibility

I possible I would like to find a solution that works in

• IE 6-8
• FF 2-3
• Safari

In order of preference.