About 3 months ago I finally upgraded from my BFG GTX 260. It still works too. So it is about time that you look into upgrading your GTX 285. I'd probably still be using my GTX 260 if it was able to play the DX11 only games, but DX10 was was its limitation. I now have a GTX 970.
Have you ever heard of the GPU hierarchy chart on this website? It can assist with comparing different cards. The 950 isn't on the list yet.
http://www.tomshardware.com/reviews/gaming-graphics-card-review,3107-7.html
Also I use hwcompare.com to compare the calculated comparison of cards. The card you're looking at probably isn't a worthwhile upgrade.
http://www.hwcompare.com/20693/geforce-gtx-285-2gb-vs-geforce-gtx-950/
CTurbo is right with their suggestion...