Searching the internet for detecting XP embedded, I found a couple suggestions. The first is to examine the wSuiteMask member of the results of GetVersionEx; unfortunately our prerequisite support offers no way to do this even under the Custom OS option. Another suggestion was to check [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\ProductOptions] ProductSuite for EmbeddedNT; this might be possible with a registry condition instead of an OS condition. Of course I don't know how reliable this is long term, across various versions of Windows and Windows Embedded, etc.
I've filed a request to widen our OS detection capabilities to allow you to check the wSuiteMask under #IOC-000081938.
