I've got a problem with Xtreme Gamer and nForce4 and I find new solution that finally works for me. I use Windows XP SP3, not Vista, but I think a problem and a solution are same.
X-Fi and nForce4 SCP problem solution (for Google) :
Go to Windows hardware manager, find disk controllers folder, look for "NVIDIA SATA" or something like that. Change driver to "standard PCI IDE" for each NVIDIA SATA controller, reboot. I get rid of crackling!
Also, this may be not only drivers, but also latest beta BIOS for my motherboard... Only latest BIOS with NVIDIA SATA drivers does not solve problem, anyway.