In need of a MacBook upgrade... Which to buy?

I have a MacBook Pro (mid-2010 model) which has the infamous video switching problem. Fingers crossed Apple will repair it free of charge with the UK 6 year cover...

I'm not convinced that the problem will not return in future though...

I'm a student so can get the student discount on a new MacBook.

I'm tempted by the top of the line 15" new model with the AMD graphics and 512GB SSD but I wanted to ask for some advice before I pull the trigger on it...

Am I going to see a huge improvement between my current MacBook Pro and the new one?

Is it likely that the graphics will knacker up like my current Nvidia one? I've seen similar in a 2008 model too...

I use my MacBook for web design, programming and a little graphics editing (with the web design).

Otherwise, would I be better off getting a second-hand one (17" model maybe?) or sticking with what I have? (if the repair lasts!).

Thanks