Strongly recommend AMD E-450
Lenovo S205 is one of the choice from E-450
Photoshop CS6 can have OpenCL acceleration on APU
which makes E-450 performs faster than Intel's main stream CPU.
If you want more accurate info should ask someone using AMD netbook
Don't know much about PS, but render 1:1 preview when importing RAW files in LR help speed up the subsequent workflow dramatically. But of course it take time to import in the first place.