On Win 7, some of the filesystem is hidden unless you turn on viewing in Explorer, I think it is Ghosterr.txt.
It does indeed sound like your WinPE boot lacks some drivers. You normally need to ensure that both a NIC driver and a SATA driver are present especially with the newer chipsets found in current hardware. The version of WinPE used in Ghost is V2 which is based on the Vista kernel and therefore needs you to provide Vista 32 bit drivers.
Also, unless you have the correct version of SATA driver, you may find WinPE unable to access the hard disk (you can always check from a command prompt) after it has booted.
For the moment, forget hot imaging and lets just work on the WinPE aspects so that we avoid confusion.
Incidentally, PCDOS is not good with modern hardware due to lack of support for SATA and inability to image big partitions (a user reported that PCDOS would not create more than 27Gb worth of image). Some bioses provide a compatibility mode that you can switch into from AHCI, which allows PCDOS to "see" SATA hard disks but this is by no means universal. Disk size can also cause problems under PCDOS.