Systems Deployment

We've got a GhostCast Server that has been running PXE and GhostCast 7.5 for quite a while, without problems. Now due to some system images coming from a sister company (for their User's in our environment) that were created in Ghost 8, we are trying to upgrade our GhostCast server to version 8. Everything seemed good except when trying to update the 'ghost.exe' in the boot image (used by PXE) - keep getting the error that the new exe is too large to use. Tried googling this, but keep seeing things about using 2 floppies (which none of our laptops have), or creating a bootable CD. How do I get the PXE image to work?