I worked with the OP via IM for a bit and we have things working for dhcp. The root cause is the dhcp config file had a wrong subnet scope defined (10.x.x.x) where the fog server was on the 192.168.1.x subnet. Once we got the configuration file fixed the target computers pxe booted without issue. At this point the OP can pxe boot the computers. He has an issue with imported images from FOG 1.2.0, but that is a story for a new thread.