Here is a nouget of goodness that everyone who does Visual Studio development should be aware of. If you decide you want the testing suite available with Visual Studio professional or the other slick little tools that come only with a paid version of the tool, you can purchase an upgrade version due to the very lenient upgrade policy. According to the VS 2008 purchasing options the upgrade is available to those using: "Any other developer tool (including free developer tools, such as Visual Studio Express Editions or Eclipse)"

The different in purchase price from Retail version to Upgrade version is somewhere around $300. 

If you are considering migrating away from Visual Web Developer to a fully licensed and operational verision then buy the upgrade. Notepad could even be considered your "development environment" if you use it for development (although that is a very loose idea of a development environment).