Hello, I'm bought a Mac Pro at the end of 2007. It is running on 2x2.66 GHz Dual-Core Intel Xenon, 4G of RAM and ATI Radeon X1900XT video card. I have been thinking of upgrading the hardware for some time, but have no idea where to start and what to get. I do a lot of 3D and high quality rendering on my Mac Pro. Any suggestions would be appreciated. Thank You.