I considered a Nvidia card simply because they have the ability to be linked together. However, given my budget, I did a cost/benefit analysis and the x850 pro was the best bang for the buck, so to speak.
As far as Intel/AMD goes, I've always been an Intel guy myself. Every computer I've had before this one has been an Intel. However, when constructing a computer, I've noticed that the motherboards for AMD computers are far cheaper for relatively the same functionality (mine has 8.1 dolby sound and a LAN card on it, for instance), and the processors themselves are similar if not better in terms of performance. So far, my FX-55 has worked absolutely astonishingly wonderful (installed WinXP Pro in 4 minutes, installs most programs instantly) and the only knocks I've had on the system have been minute (I'd like another gig of RAM and a SATA hard drive as opposed to the IDE one I got).
I'm not worried about exclusive games for the PC, either. I prefer my gaming on it (I don't know why, but I'm much deadlier in FPS' with a mouse and keyboard than an Xbox controller. So far, I've run every game I own at the very top settings without any hint of slowdown, so I'm exceedingly pleased.