@Psyk - I have the MSI 460GTX Hawk too and after installing the Tonymac nvidia drivers - mac pro 10,3 or 10,5 it works a treat! No need for NVenabler running 10.6.7.
i find the 10,3 gives the best performance - and i use wallsaver to keep from KP's.. I'm not a sandy bridge though i'm wondering...