[CentOS-virt] Slightly OT: GPLPV driver selection.

[Centos]

I'm in the middle of a (re-)install on a domU and looking for quick 
replies as too which GPLPV to use on a Windows 2008 Server install.

Windows 32bit
Xen/Centos 64bit (x86_64)

The question is regarding whether the driver to load into Windows is for 
"itself" (32bit) or the underlying hypervisor (x86_64) as in:

====
There is now one download per platform/architecture, named as follows:
     *  gplpv_<chk/fre>_<platform>_<arch>_<version>.msi
     * chk is a 'checked' build which contains debug info (please use 
these if you want any assistance in fixing bugs)
     * fre is a 'free' build which contains no debug info
     * platform is 'wxp' for XP, 'wnet' for 2003, and 'wlh' for Vista/2008
     * arch is 'x86' for 32 bit and 'AMD64' for 64 bits
====

Is the architecture ('<arch>') x86 (for the Windows domU 32bit 
architecture) or x86_64 (for the arch version of Xen running)?

I'm having a gray moment.