The difference between a Pro and a non-pro version, of the same card number, is clock speeds.
9800 Pro = 380(gpu) 340(memory)
9800 NP = 325(gpu) 290 (memory)
9700 Pro = 325(gpu) 320(memory)
9700 NP = 275(gpu) 270(memory)
I wouldnt really recommend a 9700 PRO right now, as a 9800 np is cheaper, and a 9800 Pro not much more.
Which card you choose is up to you and how much money you want to spend.
All of these cards are good/great, but honestly you will see a large difference between a 9800 Pro and a 9700 Non-Pro, so the upgrade/increase in price is fully justified in my opinion.
9800 Pro vs. 9800 NP, not a HUGE difference, and remember, all of these cards can be overclocked (however don't rely on this, only know that it is a possibility), so you could probably get the 9800 NP up to 9800 Pro speeds. Then again a 9800 Pro could overclock beyond that.
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