CPU and RAM will play the biggest factor in CS5 work. An ATI 5650 is more than powerful enough for the program for example. You need to put the money towards the best CPU and most RAM you can get.
Which in this case, I would go with the AM3 X6 CPU due to the overall cost decrease versus Intel. You can get the either X6 and 8GB RAM, cheaper than you can the i7 930 and 12GB RAM. You are looking a seconds difference, which to me isn't major but I don't make a living with CS5, so a few seconds here and there might make all the difference.
You can look to add either the Intel X25-M G2 80GB or OCZ Vertex/Agility 2 50GB SSD's for under $250. If you can stretch it to closer to $400, I would get the 100GB version of either Agility 2 or Vertex 2.
Also, you can look to go with the OCZ Vertex 2 or Agility 2 50GB SSD drive and up your GPU to an ATI 5770. This would make the system a decent gamer build even at 1920x1080 + resolution.