Its actually a good idea to remove it. If you ever run into a problem and need to boot into recovery from hboot/bootloader to flash a backup, if the PG05IMG.zip is still on the root of your sd card it will start loading that zip file. It needs to be deleted or moved to a sub folder to get to recovery to access clockworkmod and your backups.
Actually happened to me. I couldn't get into my phone (a long story) and needed to manually boot into recovery to flash a backup rom. I still had the PG05IMG on my sd card and it was automatically loading each time. I ended up having to pull my sd card out of the phone and deleting the file from my computer. Put the sd card back into the phone and was able to get to recovery and access my files once again.