nforce4 IDE RAID drivers

I just upgraded from a Chaintech VNF3-Ultra (nforce3) to a Chaintech VNF4-Ultra (nforce4), and have been having problems with the RAID drivers/software.

I am doing IDE RAID 0 with 2 Seagate 120GB drives, each as master. The IDE 0 has the Seagate as master and my NEC DVD burner as slave, and the IDE 1 is the other Seagate as master.

On the nforce3, I had no problems at all. The SiSoft Sandra 2005 FileSystem Benchmark was at 83mb/sec. After I installed my new nforce4 board and latest nvidia 6.66 drivers, I did the FileSystem Benchmark and was getting 48mb/sec. So I installed the original nvidia driver that came with the motherboard (6.39), and the benchmark was at 83mb/sec again. So all was great so I installed the 6.66 drivers again to upgrade them, but after a restart, the benchmark was even lower; it was at 38mb/sec. I am really confused now about this.
I am ready to install the 6.39 drivers again and just leave them and not upgrade to the 6.66.

Is anyone familar with this problem?
My only guess is that the 6.66 drivers aren't allowing the nvidia raid service to load.

One last note, when I had my nforce3 motherboard, the nvidia drivers installed the RAID Manager application, but the nforce4 6.66 drivers did not at first. I noticed the RAID Manager on my start menu only after I installed the 6.39 drivers (older).

Thanks for any help!