One thing to note is that applications are also becoming more video card aware. Adobe has redone all their applications so that they all utilize the GPU giving a much different environment. Before, Photoshop was pretty much CPU dependent but they are now using GPU's more extensively in CS4.
Encoding for video is also being pushed over to the GPU which translates to much faster encoding times versus just using CPU (quad or dual). refer to, http://www.badaboomit.com/
Games are pretty much limited to GPU power so if you play games, it's probably worth it to spend more on video versus CPU.