Precision T7400 with ATI corssfire ??? possible ?

Hi,

I have a PWS T7400, and want to upgrade to 2 x Sapphire 1GB GDDR3 Radeon HD 4850 X2-PCI E Cards in crossifre, but is it possible ?

Everywhere i read its talk on Nvidia SLI, can anyone advise ?

Thanks   :o)