1>d:\my documents\downloads\box2d_v2.0.1\box2d_v2.0.1\box2d\examples\helloworld\helloworld.cpp(19) : fatal error C1083: Cannot open include file: 'Box2D.h': No such file or directory
This is probably because VS2008 doesn't know where to find the include file for box2d. If you look at the source file in question, you'll see that it has a #include "Box2D.h" directive, instructing the compiler to read the Box2D.h file when compiling. The compiler will look in the same directory as the source file, but it doesn't find Box2D.h there, so it fails with that error message.
In order to get this to work you need to configure VS2008's include directories so that Box2D's include directory is on the list. To do this:
1. Select Tools / Options from the main menu
2. Click into the Projects and Solutions/VC++ Directories section
3. Drop down "Show directories for" and select "Include files"
4. Click the "New Line" button and then browse in the item that appears to the Box2D include directory (e.g., "D:\Code\Box2d\Include", or wherever you have the Box2D files stored)
5. Drop down "Show directories for" and select "Library files"
6. Click the "New Line" button and then browse in the item that appears to the Box2D library directory (e.g., "D:\Code\Box2d\Library")
7. Click OK to return to the VS2008 IDE
Once you've done this, try compiling again. This time VS2008 should know where to look to find the Box2D.h file and it should compile cleanly.