The NVIDIA GeForce GTX 560 Ti is supported in Ubuntu by the official Nvidia drivers since version 275.xx.
The driver can be installed since Ubuntu 11.10 by the “additional Hardware” tool or can be installed by the apt-get command:
sudo apt-get install nvidia-current
The graphic card can also be used with the OpenSource driver nouveau, but needs at least kernel 3.6 for this. With kernel 3.5 the card can only be used with the latest GIT version of the driver (see bug report).