I would get the new CPU. With a z77 motherboard you can overclock it and hopefully hold on to your CPU for longer, and later get a new GPU when you have the money, and get a fancy new 7xx or 8xxx cards that will be out later this year.
What type of games are you playing? Some games are more GPU or CPU intensive. One might be more important than another depending on the game.
If you get the CPU the 460 (Assuming its 460 watts) will be fine. The GPU though, you might need a change. Check the reccomended PSU stat from wherever you are going to buy the GPU. It should be good though.
PS2 is quite CPU dependant, along with BF3. The others, you will see better performance with a new GPU. Reccomending the 670, or if your on a budget a 7870 or 7950.