Some comprehensive benchmarking was done by Gary(RESET MCP ALT) over at Avsim.com.
Please visit avsim for Gary's complete commentary.
1. SP1 gives just over double the performance of RTM and SP2 adds another 10% with DX9 on Vista 64
8. A 50% CPU overclock translates to a 34% performance gain, which is an efficiency factor of 68%, on both OSs
9. Running 1066MHz FSB versus 1600MHz FSB results in neglible performance difference (<0.5%) on Vista 64