   You can purchase the upgrade to Visual Studio Professional if you use VS Express
  I thought I would post this as it is not that easy to find out on the Microsoft website and it might save someone some cash, but I was looking into getting Visual Studio 2008 Professional and apparently if you use one of the Express Editions you are eligible for the upgrade edition instead of having to purchase the full version of Visual Studio 2008 Pro. I e-mailed the Microsoft store and they confirmed it for me you just need to enter your Express edition license number when you are installing the upgrade.Hopefully someone will find the info useful as it was not made clear on the Microsoft website and I only found out about it by chance.   