Rectangle ads in the content articles

suggestions needed

[benevolent001]

Hi
I have a query,how do you display the rectangluar ads within the articles and the article text takes place of the text in case ad is not available.

I tried to make it using two column table and placing content on left side and ads on the right side,it works fine if we have fixed size of rectangle (say 250*250 i fixed)but if the ad size is changed later and show bigger recangle the text on the left side will not cover the whole column and some portion of the column will be left uncovered

I hope I am clear to you and you will suggest something for this

It would be good if you can give me some code or layout suggestions

Thanks for your time