Mac {ro or Retina MacBook Pro - which to buy?

Okay so here we go - I have the opportunity to buy either the mac pro 2009 and upgrade it exactly like "wonderspark" here on macrumors has done - from the 2.66 quad to the 3.33 and add more ram, more hard drives and a better graphic card..

I can get a mac pro 2009 with quad with 2.66 ghz, 8 gb ram, 2.8 tb of hard drive space for about 1300 dollars..

Or I have the possibility to get the macbook pro retina 15,4 2,3 ghz, 8 gb ram, 256 ssd. for about 1200 dollars..

Both are used - what would be the best choice?

I would use it for mostly photoshop cs6 and capture one, because I'm a photographer..
I do occasional gaming and other stuff - but really I just need a fast maschine that would follow me at least the next 3-4 years..

Currently I have a macbook pro 15" 2.4 i5 ' and a macbook air 13" and a cinema 27" display.. I would opt to have the most juice for the money.. And mostly a workstation..

Is the new macbook pro retina really faster and a better choice than an upgraded mac pro 2009 -
to intel 3680 - 16/32 gb ram and a 128/256 ssd drive?

Please help me out guys - I have just 5-6 days to make the right choice..

Regards in advance!!

Malthe*