You need a pretty beastly GPU to run on a 55inch. I would go for a 2gb or a couple 1gb in sli/xfire.
You're going to have trouble reading text as well.
These are just predictions however.
Actually, it does'nt matter what gpu you have. If your card supports 1080p, a monitor is a monitor....so..yeah.
As far as reading text, it will be hard to read text from 11' feet away on any resolution. I have my pc hooked to a 55" LED but I sit dangerously close anyway :P