If you overclock that gt430 a bit you can get in the 30kh/s range.
I currently get 36kh/s on my gt430 with configuration 20x8.
and how do i do that?
Google a tool called NvidiaInspector (I think it's from TechPowerup). It will let you adjust the fan speeds, voltage, and clock speeds of the core/mem/shader of most all nvidia cards.
I use it to set the clocks on my gt430 card to 882Mhz core, 810Mhz mem, 1760Mhz shader, .990v. That combo yields between 36kh/s-38kh/s. If I go any higher than that I get the driver crash.
Your mileage may vary though on the clock speeds you can attain. I have an EVGA GT430 so I'm not sure how it compares to other flavors.