3-Column layouts don't always have to be table based. I had a client who purchased one of the older Project Seven Design Packs, and wanted to update it to load a little quicker and be more standards based.

Take a gander at this Project Seven mod (not sure they're selling this particular DP anymore) I did for RobinChang.com. All of the tables were stripped out and redone with a clean, full <div> layout. I was able to keep the PVII effects intact and it's nearly impossible to tell the difference between this and their original tabular form. And, it validates as XHTML 1.0 Transitional of course.