7950 = r9 270
The 280x is significantly faster than the 7950/270.
I would pass on the 7950 though and get the newer model. You probably get a free game and the 270 is easier to overclock and is a tad more power efficient. That being said they are essentially the same card.
Both the 7970 and the 7950 can play any game at 1080p on ultra with over 40fps.
Check out ebay ... coin-miners are selling of 7950/7970 for $150. You can get a r9 290 for about $200