From what I understand you have encountered problems after doing a BIOS update. If so, I would suggest clearing the NVRAM by following the procedure I have listed below. Sometimes after a BIOS update the newer BIOS version may have a conflict with information that is stored in the NVRAM. This conflict can cause boot up problems.
Keep in mind that clearing the NVRAM will default all your BIOS options back to their factory recommended settings. Not really a big deal since you're probably using most of the factory settings anyways. The defaulting will require you to re-enter the time/date, re-adjust your boot order if you have made any changes, re-adjust your power management options if you have changed them, etc. In otherwords settings that were changed to your personal liking will have to be re-set. If your system doesn't have a floppy drive the defaulting will turn on the floppy drive controller. If this happens and you get a Diskette Drive error on boot up then simply go into the BIOS and turn off the option for the Diskette Drive. The error message will be gone on the next reboot.
What BIOS version did you try updating to? A09 is the latest and last BIOS version Dell has released for your model. If you have that version installed then there is no other version to update it to.
If the system is successfully booting and the blue screens are appearing when Windows is loading then you very possibly have a problem with Windows.