iMac - processor or GPU upgrade?

I'm moving to Thailand in a month's time and sadly due to disgusting Thai import duty rules, I am going to have to ditch my lovely Mac Pro and buy a new Mac out there. I can't afford to get another Pro with all the trimmings, so it looks like I'm going to have to go for an iMac. I know there is potentially a refresh coming soon so this may be null and void, but I will HAVE to buy a computer by the end of September, possibly sooner. Looking at the current range, I know I need a 27 inch iMac, and probably the top of the line model (with the AMD 6970M 1GB). I will increase the RAM to 16GB myself (Apple prices are crazy) but my question is this; for graphic design work (Photoshop, Illustrator, InDesign and Flash mainly, possibly a little Blender 3D work) would I be best off upgrading the processor from an i5 3.1 to an i7 3.4 OR the GPU to have 2GB instead of 1? I'm not sure which would be most useful in day to day graphics work. Sorry, long question but some assistance would be brilliant please! If in fact I could go for a lesser machine (with the 6770M w/512MB) that would be great as budget is an issue... Cheers!

 

I would absolutely much rather keep the mac pro and know I could take it, but import duty could be 30% of the value-what with how much it would cost to ship it just makes it too expensive to bother with