Im new to it also but maybe i can help you.
Try other Sata Ports
Try another HDD
Format your HDD in Windows very slow. Not fast Format.
try when you go from iBoot to the snow leopard version -x, -v or both together dont know exactly
There is a command like disk0s2 or something.. google it right
This command is to load your disk or something.
diskratio=??? google it also.
maybe helps you.