Well you won't find a hacked SLI driver, I can almost guarantee that.

As for the P7N Diamond, my board and Q6600 is capable of 450x9 and perhaps more, but to be honest, OC success has been inconsistent for most. Hardware wise, it's a fantastic board, but it's limitations have been due to a strange and immature BIOS. The BIOS has improved tremendously since the board's release, and I have no doubt that in time the P7N will be a great OCer for all (I just hope that this will be before we all switch to Nehelem.) However, right now 450x8 may be a bit of a gamble. The board is more than capable of it, but even the latest BIOSes are somewhat hit or miss.

If you want excellent hardware and can handle a difficult BIOS, the P7N will do you well. If not, a 750i board, such as the EVGA 750 FTW may be your best bet. As for the video corruption issues (which I believe effects all boards,) nVidia is aware of the problem and is scheduled to release a fix by the end of the month.