One of the tools ASP.NET should come with is a tab control. Since it doesn't I end up creating my own way to do this. I am sure there are components you can buy that do the same thing, but where is the fun in that? Instead I have created a code generator that you can use to create a "Tab Control". Once you drop it in your page make sure to put some content in each View control. Also you should specify an ActiveViewIndex for the tabViews control (usually 0).
Simple ASP.NET Tab Generator