I basically only consider CPU upgrades when my GPU starts staying way below maximum load even if my framerate isn't maxed out. CPU speed for everyday things like file compression and just normal internet stuff is rarely an issue. I also use Adobe Lightroom, but I have a feeling that RAM bandwidth has a bigger impact than CPU speed there, considering the enormous amounts of data that needs to be transfered from RAM to CPU every time I change a tiny little color adjustment value on a 20+ MP RAW file. Photoshop seems to use higher amounts of RAM and more CPU, but doesn't need as high bandwidth. I've got a 3GHz i5 myself, not even sandy bridge i think.

btw feel free to send me your 560 cause I've only got a 460