Here is what I would do. Try using this image instead:
pfSense-memstick-serial-2.0.3-RELEASE-i386-20130412-1022.img
I currently have this on an MX1004, and it works on the MX0804 as well, one a Intel Celeron 600 MHz and another the VIA 1 GHZ C7. We work with IBM devices, including the GX3002, but since they are now obsolete, our company gave them away for free, otherwise they will go to the shooting range (yes I know).
I'll also test this out on a GX here that we no longer need to verify it works when I get the time. I'm pretty sure it should work fine if its x86 arch.