Hi, I've just purchased an ATI Radeon HD 4870 graphics card for my mac pro. I now have the original graphics card for the Mac Pro spare, the ATI Radeon HD 2600 XT Graphics Card. I'm wondering if I can put the old Mac Pro card in my ageing G5 power Mac which currently has ATI Radeon 9600 Pro card? And will I see much improvement if I do? Thanks.