Hi,
Really strange, because when you create a VM using vsphere client and select Windows Server 2003, the guestosidentifier located in the vmx file is winNetEnterpriseGuest. My guess is when you create a vm using SDK you need to provide the OS version. But the VMware tools's binaries are the same. So, you can choice winNetEnterpriseGuest or winNetEnterprise64Guest.
Regards,
Julien.