doesn't matter if the drivers are up to date.
the GTX 550 Ti is not that good and not a gamer card, even in SLi the 550 Ti is only a GTX 560 Ti just short of a GTX 560 ti-448.
but at least with the -448 you have 1.2GB of VRAM while even in SLi the 550 Ti's only have 1GB.
I use the 550 Ti in a HTPC and I use it as a PhysX card.
Skyrim eats VRAM from the start of the game.
then you have a FX-8120 processor on top of that to compound your lack of FPS..