939a 785GMH enable crossfire XP?

[b wizz]

Could someone please clarify if windows xp supports crossfire . says in my manual that it is supported by only windows vista onwards.
but information on the web implies that crossfire is supported , I have followed my manual step by step to enable crossfire with the onboard Gpu
and a 4670 hd card . I don,t have an enable crossfire option in the latest catlyst driver software.
thanks in advance