Today I had to generate an xsd (xml schema file) from an existing xml file.
In the past, I had used xsd.exe, which lived in the SDK directory of VS2008.
As I do not have VS2008 installed on my current machine, I had to go hunting for it. On a Windows 7 machine running VS2010, xsd.exe should be found in:
C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\bin
C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\bin\x64
You can then run this application from the command prompt in order to generate an xsd file, as per the usage instructions on msdn here.