Like NDPetty, i'm having issues with this too. Installing XP on the HP DC7800 SFF, I know the image works as it works with a HP 8000 Elite SFF. I'm using SCCM 2012. I assume my issue is a combination of having the incorrect Mass Storage Driver defined in the Driver Package or the BIOS config is incorrectly set.
There are 2 choices in the BIOS, RAID or Emulated IDE.
If i boot in safe mode after a failed OSD deployment attempt, it doesn't make it pas iastor.sys.
If i look on a machine that has XP installed correctly, the device manager looks the same as matt_isda_bomb's post.