If you're out of warranty, the battery is your best place to start.
You can use Win7 32bit, as the Dell Vista drivers are compatible with it.To elaborate on what Systech said, sometimes the BIOS goes through a version update simply to follow a hardware update.Most BIOS updates are only necessary when new hardware is not detected at boot. The first one updated the bios on vista 32bit with no issues. Event then those are rare cases, and mostly result in updates past the products intended life-cycle. I'm running the flash utility as an administrator and I've tried all of the compatibility settings.
Does anyone have any suggestions on what I can try to update the BIOS on this machine?I believe the BIOS is therefore the least of your future worries.I would really advise to go back to a 32bit OS, as a 64bit OS won't have any appreciable advantage on this machine.Then install the Windows-only BIOS Flash upgrade and upgrade the BIOS.Then swap your original drive back to use your 64-Bit Windows.Dell should have also understood why you can't update the BIOS. I'm not sure if this needs to be pointed out--but put the battery in and plug in the AC adapter when you're updating the BIOS. Somehow the system recognizes the battery is lower than 10% and it won't let me update the BIOS.