I downloaded some sample ASP .NET projects from net. But they are in VS2010 format. I use VS 2008. How can I change the format?
If you take a 2008 project and migrate it to 2010, only the .csproj, .vbproj, .sln files etc will actually change. So in theory you could try to edit these back to 2008 values. However, the actual code in the samples may be aimed at a different version of the .NET Framework than you have.
I would recommend creating a new ASP.NET project in VS 2008, then using Add, Add Existing Item to add the pages, config files etc from the samples into your project. Then edit them to fix any issues with using functionaliy you don't have.
Or better still, go find some samples for the version of VS and the version of the .NET Framework that you are actually using.
You can try to create a brand new solution and create new projects from the existing source (File | New | Project From Existing Code). However, if they're using any .Net 4.0 features (or certain C# 4.0 features like dynamic) then you'll be out of luck.