I installed a copy of 10.5.6 using iDeneb 1.4 and on boot up I get this message

boot0: GPT
boot0: HFS+
boot0: booting
boot0: done
boot1: error

My system is
Core 2 Duo E8500
Asus P5Q-E
4gb OCZ Reaper
Nvidia Geforce 260gtx