The problem isn't with PXE. PXE just means "boot from network" and has nothing to do with your issue - your really issue is the GUID partition table which would break a Windows installation done via MBR. When you converted the partition to GUID via testdisk and then rebooted, you lost any ability to use anything other than PC-BSD, being the only GUID-capable installation you had on your disk.
What you need to do is boot into PC-BSD or a Linux live CD and use testdisk to search for and recover MBR partitions. You *may* have broken it permenantly by trying to force bootrec, I do not know.