From what I've heard, Ivybridge is going to have better integrated graphics than Sandybridge, but the performance isn't going to be hugely different in terms of the CPU. It'll probably be better, but maybe not so much that you would get a hugely better chip for waiting. Sandybridge-E will be the one to go for if you want better performance than Sandybridge.
Your current rig looks good...you could just upgrade the graphics card for now, and wait to see what CPU you want to go for. The 600 series is due next from Nvidia, but the current generation of cards is excellent, too. Or you could SLI your current 460 (if your motherboard supports it?)