VS2010与VS2008相互转化

 http://www.codeproject.com/Tips/319568/Converting-VS2010-Solution-to-VS2008#alternative3

If you are working with VS 2010 (any edition) and cannot open your 2010 solution on VS 2008, then just follow these 3 steps:
 
For <PROJECT_NAME>.sln:
 

1. Open the solution file in your favorite text editor (ex: Notepad++).
   
2. Find the following:
   Microsoft Visual Studio Solution File, Format Version 11.00.
   # Visual Studio 2010. 
   Replace with:
   Microsoft Visual Studio Solution File, Format Version 10.00. (I)
   # Visual Studio 2008. (II, optinal)
   

 
For <Project_name >.csproj/vbproj:
 

1. Open project file in your favorite text editor (ex: Notepad++).
   
2. Find the following:
   <Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">.
   Replace with:
   <Project ToolsVersion="3.5" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">. (III)
   

That's it.
Now you can open your solution file on VS2008.
Reverse of this will enable VS2008 solution to open in VS2010.
 
EDIT

---

After these changes, you may receive the below error:

 Collapse | Copy Code

---------------------------Microsoft Visual Studio---------------------------Unable to read the project file 'XXX.csproj'.  C:\Project path\XXX.csproj(89,11): The imported project "C:\Program Files\MSBuild\Microsoft\VisualStudio\v10.0\WebApplications\Microsoft.WebApplication.targets" was not found. Confirm that the path in the <Import> declaration is correct, and that the file exists on disk.---------------------------OK   Cancel   ---------------------------

To fix this error, just change the VS version(v10.0 to v9.0) in your <Project_name >.csproj/vbproj file, that's all.
 
Good luck with it.