on the asus p4p800 i have it will always default to booting from the most recently installed drive, be it ide, or usb
to correct this enter the bios setup, choose the boot option, then from harddisk drives pick the original pata hdd, thn goto the boot devices priority and check the newly selected pata drive has become the primary boot drive, if not hit enter on the primary entry and select the pata drive from the list
also in the main bios menu check the ide configuration menu is set to enhanced mode, otherwise the bios will disable one of the pata channels when the sata drive is installed
.:xigma:.