radeon X300 Snow Leopard Driver

I recently won a 32" TV so I decided to hook it up to my early 2009 model Mac Pro running Snow Leopard 10.6.8 (They need to update their drop down below). I have a 24" Dell ST2410 connected to DVI and the 32" TV connected through HDMI on the stock graphics card, an NVIDIA GeForce GT 120. I have another Dell ST2410 that I'm attempting to hook up through DVI on an ATI Radeon X300 graphics card I had laying around. The X300 works fine in my Windows 7 Bootcamp installation but isn't recognized on my Mac Pro.

I love the way hardware on a Mac just works but now that it isn't I'm sorta left in the dark on how to fix it. Viewing other posts on here it seems that people have been able to use that card in OS X. What do I do to get it working?