Becareful of fanboys the 460 trumps the 5830.
The 460 is 2-4 times faster than a 8800 GTS 512MB. It's also quiet, low heat, and great for gaming. Of course it also depends on which 460 you get. the 1GB version is faster than the 768mb version. There are some cards that come overclocked also. In benchmarks the 460 is close to a 5870 but the 5870 is maybe 2% faster. It depends on which OC version of the 460 you get too. It could be faster in some instances.
How does the gtx 460 compare to gtx 470,480,465 and the gtx 260?