Microsoft recently released a new set of chart controls for Windows and Web forms for .NET 3.5 SP1. However, to install and use them in Visual Studio you need to download and install a minimum of two different downloads and an optional third.
The first one is the main update for .NET 3.5SP1 available here. If you need Visual Studio 2008 SP1 support you need to install the add-on from here. If you need the full documentation, download and extract the file from here.
Once these are setup, you can add the Chart control from the Data group in the Toolbox. Add a data source, set the series data points in the properties and you are done. Quite easy to start creating dynamic charts on your site without any expensive 3rd party solution.