If you evaluated Visual Studio 2010 Beta 1, you will be happy to hear that no reformatting is required. Additionally, a simple path exists to upgrade Beta2 on the same machine. It involves uninstalling your Visual Studio 2010 Beta1 product and then installing one of the Visual Studio 2010 Beta2 offerings.
Given the nature of pre-release software, there may be a few pre-steps needed to ensure success, depending on what operating system you are using or what you have installed on your machine.
Here is a quick guide to upgrading to Beta 2. (These steps need to be performed in this order).
1. If you have Visual Studio Team System 2010 Beta 1 installed: go to Add/Remove Programs and uninstall Microsoft Team Foundation Server 2010 Beta 1 Object Model.
2. If you have Silverlight SDK 3 installed:, go to Add/Remove Programs and uninstall it. (It's often installed with Expression Suite 3 or as an add-on to Visual Studio 2008).
3. Everyone: Go to Add/Remove Programs, Uninstall Microsoft Visual Studio 2010 Beta 1,
4. If you are using Vista RTM or SP1, or Windows Server 2008 RTM: then go to Add/Remove Programs and uninstall .NET Framework 4. That would include any associated langpacks, Extended, and Client, in that order.
Everyone: Now Install Visual Studio Beta 2!
For full details about these issues, you can read the official Visual Studio 2010 Beta 2 ReadMe here.
See the following help documentation link for more information on how to install and maintain Visual Studio Beta 2.