Hesitant of getting higher resolution monitor with my current GPU...

Background info - I game on "HDTVs", 40" or higher, to me they are just big monitors so I just call them that, my GPU is an HD4870

I currently have an 40" monitor which is 1360x768, the resolution was good at the time but I want more now, I want something bigger like 50" but the resolution has to be higher if I'm gonna blow up the screen size by 20%

My only option with such a size is 1920x1080, I dont think there is any other option for a 50" display. I am afraid of two things...

1360x768 is a "standard" monitor resolution, 1920x1080 is not, am I gonna have issues with games where I'm gonna be forced to use a non-native resolution of 1900x1200? I've never seen a PC game with an option of exactly 1920x1080.

And finally performance, I have been using a fairly low resolution since I've had my current monitor because its only 1360x768, I cant afford to have the highest end $600 video cards so I think I will have framerate issues, I do not like running low non-native resolutions, and I realize I will get a sharper picture but framerates are equally important. I have an HD4870 right now, I know it's a pretty good midrange card but do you think it will handle 1900x1200-ish resolutions fine in demanding games for the next year? How much of a performance hit can I expect with the increase in resolution?

TY

I think the 4870 may handle 1920*1080 with no filters (AA or AF) at medium or high setting, if it doesn't you should consider adding a second 4870 IMO