Intel processors work a lot differently to AMD processors, it isn't always about the Ghz or the cores, the best Intel processors tend to be better than the best AMD processors.
I would say that Intel are slightly more expensive for the performance you get, you can compare processor benchmarks here http://www.cpubenchmark.net/.
With that budget, I wouldn't be afraid to splash out on a high end Intel i7.
The graphics card mainly depends on the type of game you want to run and at what resolution.
The Witcher 2 maxed out @ 1080p would need a GTX 570 or an ATI HD 6970 for it to run smoothly.
If you have a lower resolution monitor or you do not want maximum settings then a GTX 560 or an ATI HD 6950 would be fine.
Again, with that budget, I would recommend you go for the high end graphics cards.
