Comment 14 for bug 75055

There is a problem with ATI SB600 SATA drivers on AMD64 (Atleast I had) if you are using 4GB+ RAM. I had the same problem of drives not being recognized and I found a detailed explanation of the the issue @ http://<email address hidden>/msg06310.html (follow the whole thread)
This problem is still there in 7.04 Fiesty AMD64. Reduce the RAM to less than 4GB (Remove 2GB) and install. Once the installation is complete add the kernel parameter 'mem = 4095MB' in the GRUB configuration. This worked for me.