In my testing, the NVIDIA GeForce GTX 560 Ti with 448 cores is about as close as you can get to being as fast as the GTX 570 without embarrassing it. In a couple of our lower resolution tests, the new card was in fact just barely faster, but usually within a margin of error we were comfortable with. Most of the time, especially in games that we know are super GPU dependent like Battlefield 3, the 448-core variant was reliably about 3-5% slower than the 480-core part."
Any major computer upgrade generally requires a full software reinstall too. No so if you heed the advice in the guide to Upgrading a Motherboard without Reinstalling. PCSTATS Tips