Here is a review with 1920x1200 for SCII
My thoughts are that it would run at 1440p with acceptable FPS (maybe have to turn a setting or 2 down a notch), BUT, its going to be cutting it close an may require replacing sooner than you would like because of the resolution. Personally if you are sticking with Nvidia I would say minimum gtx 660 (non-Ti) for that resolution and primarily SCII. I know its not as cheap as the 650Ti, but at that high of a resolution the 650Ti is cutting things back a bit too much. If you were planning on a 670 then its still a massive savings to go with a 660. As much as the 650Ti may suffice I think its worth the extra few $.
AnandTech - The NVIDIA GeForce GTX 650 Ti Review, Feat. Gigabyte, Zotac, & EVGA 