Monitor resolution? I don't think medium graphics on new, demanding releases are possible even now without uncomfortably low framerates at 1080p. In three years, your card would be very slow, barely enough to play new releases on low settings.
Yeah, D3 and SWTOR are both pretty easy on the GPU.
However looking at performance reviews, average framerates for 5770 seem to be only about 38fps in D3 and 45fps in SWTOR on high settings. Well below what I would subjectively call playable. I think a minimum framerate of 45-50fps is still acceptable, average needs to be close to 60.
Chances are, you'd be able to replace it in a year or so with a decent card for around $100. You may even be able to sell off your current card for $40 or so at that time. Hold off until you start to notice yourself getting irritated in games due to graphics performance. Once that happens consistently, then look for your upgrade. For some, 30fps is "fine". Don't get hung up on the number though. It's always based on how acceptable your experiences are.
I think you are reading the wrong card for D3 (6770 is closer to 5770 than 6670 AFAIK).
I've got a 5770 - it ran Deus Ex HR at 1080p without any problems really. Not that DXHR is the most graphically intensive game, but its not bad.
Personally I'm not buying until I see a real benefit from a card for a similar price. The 7770 is around the same level of performance, but its not much cheaper than what I paid for the card, while the 7850 is significantly more expensive. I'll upgrade when the same amount of money gets me significantly more GPU. Probably the next generation of cards then.
not true the HD 7770 is around the performance of the HD 6850 not HD 5770 or HD 6770
http://www.anandtech.com/bench/Product/538?vs=536
I stand corrected!
Not enough of a difference for me to justify upgrading, besides, if I'm totally honest, I dont play that many games these days.