I know it's a stale thread, but I found a work-around for this. I too have the P5N-E SLI and wanted to upgrade to an SSD. The deal that seemed good at the time was the Kingston 96GB V100+. After struggling with drivers and cables and all that, I started finding these threads around the internet. Since I didn't want to hassle with sending the drive back, and I had to get back up and running soon I decided to try an add-on controller card.
I picked up the SIIG SATA II PCIe (SC-SAE012-S2) from a local store for $40. My choices were a bit limited since I was pressed for time, so there may be comparable cards out there for less. The driver had to be loaded from the CD during the Windows installation, but after that it has been smooth sailing, it even shows up as a bootable drive option in BIOS.
So far so good...