Dude, I really didn't want to upset you. You just remained me in 2009.
Then I used to have E6300@3.5ghz, 8GB ram and then I just bought new and shiny GF8800 Ultra. I got same ideas (and excitement) that you have now, then after 6months one great programmer contacted me and explained me alot about gpu computing. He actually did write some kind of CUDA code to accelerate his EA optimization (He had GF9600GT). Basically what he sad to me is this:" GPU computing is so extremely parallel that It's just impossible to make GPU calculate whole thing (like cpu do it), only some input parts can be calculated by GPU.
Just wanted to say that then I would be extremely happy if cloud existed. Back then you couldn't do alot if your means were to build expert that could work great as long term investment. Now you can!
BTW: What card do you have? I know it's not Ares 2 because you are talking about CUDA. :D
As for MQL5 and Open CL you will be better of with Radeon. If I compare with bitcoin mining hardware(also huge open cl guys on gpu computing).
GTX680 gives ~120 Mhash/s
HD7970 gives ~680 Mhash/s
So it's about 5.6x times better for AMD gpu.
Btw: your gtx580 have faster calculation than gtx680. 140 Mhash/s