Hi.
Do you have a registry key "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\15.0\Outlook"?
If so, please check the value "Bitness".
If not, you haven't installed Outlook, so WOU defaults to x86, since this reg value seems to be the only way to properly detect the Office architecture.
Anyway, the cab files WOU applies after SP1 should install fine since they're independent of architecture.
Regards
T. Wittrock