Can anyone suggest the best laptop for heavy photoshop and corel painter 12 use? With a budget of £500 or less.

I am having to replace my current samsung r530 due to constant power problems and it crashing with painter 12. I have only had the damn thing 2 years :( can anyone suggest a better replacement? i am an artist/designer who travels a lot so though I know a desktop would offer better spec for the money its just not doable for me.

All suggestions welcome especially if they come with explanations and links. Thanks in advance!