During my last workshop class on ASP .NET we had a review on web page design with ASP .NET. One of the most important part of the design is positioning the element inside you web site. What I recommend is to use <div> and <span> element with CSS styles to position your web pages instead of <tables>. If you look at the many professional designed web sites (like yahoo,msn, ...) and check their source code you will be noticed that most of them are using <div> or <span> for their pages. If you want to know why? "Table vs CSS" is are the reasons.
Now let start with learning <div> and CSS positioning. Just like always I recomend W3Schools. The next one is a reall great weblog from Big John, positioniseverything.net. It's nice blog explaining about positioning with CSS and bugs of browsers.