Which modern cards equate to a GTX 275?

My Nvidia GTX 275 serves me quite well still, but lately I've started thinking about an upgrade. I'd quite like to know what kind of performance gain I'd be looking at though, but of course no current reviews include the 275 among the references.

However, perhaps someone can tell me what current card(s) perform approximately on par with the GTX 275?

@ around 1920x1200

Its smack between HD5770/GTS 450 and HD5830/GTX 460 (768mb).

Thanks shaithis, much appreciated!