The reason is because the file is not actually in the linked location. It should be in this folder, which it is not:http://ftp.dell.com/FOLDER00416156M/1/
The same file (original location) is here:http://ftp.dell.com/sas-raid/RAID_FRMW_WIN_R189337.EXE
Don't forget to update the RAID driver before the firmware:http://www.dell.com/support/drivers/us/en/RC1232625/DriverDetails?DriverId=M4F88&FileId=2953961059&DriverName=Dell%20PERC%205%2FE%20Adapter%2C%20PERC%205%2Fi%20Integrated%2C%20PERC%205%2Fi%20Adapter%2C%20PERC%206%2FE%20Adapter%2C%20PERC%206%2Fi%20Integrated%2C%20CERC%206%2Fi%20Integrated%2C%20PERC%206%2Fi%20Adapter%2C%20PERC%206%2Fi%20Integrated%20Blade%2C%20v.126.96.36.199%2C%20A03&productCode=poweredge-1900&urlProductCode=False
If that doesn't work (which it does for me), you can get that here:http://ftp.dell.com/sas-raid/RAID_DRVR_WIN_R210510.EXE
Ideally, you should also be doing these updates after updating the BIOS and ESM/BMC firmware.