100% Height works in ie but not ns

Hi

I have a 3 column web site, left, middle, right. As each page within my site will be a different size, i thought i would set the height for the left middle and right to 100%,

It works but only in ie, also i am pretty convinced the way i am doing this is a bit shoddy, does anyone have any answers or solutions for me

much appreicated, you can look at one of the pages here F:\search-engine-professionals.co.uk\pages\campaigns.htm and save it to look at the css

p.s. the css is in a bit of a mess at the mo.

Sorry wrong address here it is http://www.omegadm.co.uk/promotion3.htm