Being a Dell OEM, I would not expect a BIOS update to provide support for "newer & better" CPU's. This would make their PC's upgradeable beyond what they want. Meaning, they want you to have to buy a new PC instead of upgrading
Also, I'm not aware of a BIOS update that will increase the FSB speeds. FSB is driven by the chipset not the BIOS, as far as I know. If anyone knows different, please feel free to correct me