This looks like a critical driver is missing, and I would suspect that perhaps your boot environment lacks a device driver for the SATA hard disk in your system. If your bios has a hard disk "compatibility mode" setting which allows a SATA hard disk to emulate the older parallel ATA standard, then you could try PXE booting with this setting enabled and see if it fixes the problem. If it does, then at least you know that the answer is to add the correct Vista 32 bit driver to WinPE for your SATA chipset (Winpe uses Vista kernel so needs Vista drivers). The same applies to your NIC chipset - PXE booting uses a standardised method to read the initial boot loader file, but you still need a valid WinPE driver for the LAN NIC chip in your system so that WinPE can access the network once booted.