Logging any client into the SBS 2003 domain runs setup.exe from the server. This may be something to do with AD, but I cannot be sure.
My client has purchased a Windows 7 64 bit PC (little else available) and whilst it works on the domain perfectly, every time someone logs in the error message that 'setup.exe' from the server is incompatible appears. It is easy to cancel and does not seem to create any issues, but it is an annoyance.
Of course it is obvious that a 32bit piece application from the Server will not run in the W7 64 bit environment, but I cannot find anyway of stopping the W7 64bit system trying to run it.