i can't believe that i am about to say this, but... you may want to contact dell support and see if they offer a Bios upgrade for the 1100. tell them you are a technician and they will send you to a little more advanced computer help.
If you are just trying to put the 5150 BIOS on the 1100 you might be able to download the Bios update for the 5150 and flash it on the 1100. i don't see why not. as long as the 1100 and the 5150 have roughly the same hardware on the board it should be ok. it is worth a shot.