For several years I've been through a few different graphics cards.
First, I had an old nVidia GeForce 5900 (I think). Then, I switched to an ATI Radeon 9700 Pro. Then a nVidia GeForce 6800 Ultra, and then the ATI Radeon HD 3850 Pro that I have now.
In my opinion, nVidia greatly surpasses ATI in terms of stability and installation.
However, I am quite satisfied with my current graphics card, being able to run Fallout 3, and most other new games. Hopefully, soon my dad will buy a better graphics card, so I can have his awesome nVidia GeForce 9800 GTS.