<p>Can a WinForms app compiled for "Any CPU" be configured to run as "x86" on a 64-bit server without recompiling the app? Specifically, I'm looking for an app.config setting or Control Panel applet to accomplish this end. All the customer's clients are x86, but the server is x64, and we like to install the WinForms app on the server for administrators to configure and monitor the system. We would much rather not recompile just for the server.</p>

From
http://www.request-response.com/blog/PermaLink,guid,34966ef8-3142-46b2-84e0-372b5c36ddcc.aspx
You can, however,  control and
  override this default behaviour even
  after your code has been compiled.
  There's a handy tool called
  corflags.exe present in the SDK that
  allows you to force 'anycpu' compiled
  code to use 32-bit process in 64-bit
  world.
The usage of this utility is found here
http://msdn.microsoft.com/en-us/library/ms164699(VS.80).aspx