Re: 260 -> 460, how much faster?
I just went from an Asus GTX 260 192sp to a Gigabyte GTX 460 OC 1GB and the performance gain is very noticeable. I could play Starcraft II with high/ultra 2x aa at ~50fps before.. now I can play it with full ultra, 4x aa at over 60fps. While trumping the old card it's still much quieter and runs cooler.
It is also extremely applicable to overclocking. I bumped it up +130mhz core and +100mhz memory right out of the box and it's rock solid. Feels like it's still a huge headroom for more overclocking. Probably up to 10% more.
The GTX 460 is a winner. I really recommend it.