Originally Posted by Tommy Boy
The video card has no bearing on how well your actual computer runs, just the graphics performance. You could put the absolute lowest end card you can find in a screaming fast computer and the only thing it would affect is the graphics. The graphics card is a completely independent system.
Not entirely accurate. If you get a low end enough card, especially with low RAM, your overall system experience will be much slower. Take a high end PC sometime and equip it with the low end cards out there now, and then throw in a high end card, and you'll see what I mean. We do this all the time at work when we get systems built - we usually build up a system with our generic low end GPU, and then install a high end unit when it either arrives from shipping, or if the user requests one after-the-fact. Different RAMDAC speeds, RAM sizes, GPU acceleration features, etc. It's a lot better than it used to be, but there is still a subtle difference now.