best way to design for multiple resolutions (datagrid)

[tebathe3]

I am attempting to make a scrollable datagrid with a fixed header:

http://datawebcontrols.com/faqs/CustomizingAppearance/ScrollableDataGridWithFixedHeader.shtml

Basically the idea is placing a table row above a datagrid to create the fixed header.

It works fine, but I have to specify a pixel width for the table cells and the datagrid columns. Looks great on my machine, but on other machines (with the same, or with a different resolution) the columns are not aligned properly. what is the best way to specify size so that it will look correct?

 

[tebathe3]

also, if possible, I would like the solution to work in firefox and IE.