The overall benchmark rating comparison between the Radeon hd 8280 and the Nvidia 610 GT 2g puts the 610 just slightly higher then the 8280. From the looks of it though it won't make that much of a difference, the scores are literally points apart so personally I'd say if you can swing the extra funds upgrade to a higher Nvidia 700 or 800 series. I just picked up a PNY NVidia 710 for a few dollars more then the 610 GT 2G cost me years ago and so far have been really pleased with the results.
You can use this website to check the card differences any time by the by: http://gpuboss.com/. If you do the 'compare' against the NVidia 710 you'll notice right away that for the extra 5-10$ it's worth the investment (esp if you're like me on a small budget and still crave comparably good graphics). Good luck with your upgrade! :)
PNY - NVIDIA GeForce GT 710 VERTO 1GB DDR3 PCI Express 2.0 Graphics Card - Black
(154)
PNY - NVIDIA GeForce GT 710 2GB PCI Express 2.0 Graphics Card - Black
(1,178)