I discussed Figure out the bitness of a process and the ProcessorArchicture of the system back in July 2005.
If you just want to determine the processorArchitecture of the running process from managed code, there is an easier way in .Net framework 2.0.
public class test
public static void Main()
This takes advantage of the fact that mscorlib.dll is a platform specific assembly in .Net framework v2.0.