Save your money and buy the cheaper card. You could easily overclock the card 24MHz more and achieve the same performance. However, only overclock the cards if you're able to keep your GPU temps down. If they run too hot, the overclock will be ineffective, because the programming on the GPU will automatically turn down the clock speeds if it gets too hot. The twin frozr will be cooler though.
If you are sure that the twin frozr fans will cool the card better, then I am going to get the twin frozr. How hard is it to overclock cards? Again, I'm still transitioning from console gaming, this stuff is still a little new to me. You use the driver software to raise the clock speed, right?