Run from dvd with -v option an see what chipset are using for installation. then check it at install options.
For example.. I have an SB450, but when I installed I could see "ATA VIA chipset".. so, first time installed I dont check "VIA CHIPSET" and when I reboot ... "Still waiting for root device" message occurred.
Second time install, I check this opcion (VIA Chipset) and... leopard is running
Sorry for my English. I hope your leopard running

Gaston