UEFI BIOS vs BIOS
The last Dells to support Windows XP were the OptiPlex 3010/7010 which have a UEFI BIOS and Secure Boot. To install Windows XP on these models, Secure Boot needs to be Disabled and a Legacy Boot needs to be selected with Legacy Roms Enabled.
The Dell Optiplex 390/790 also have a UEFI BIOS without Legacy Boot. For these models the Boot Mode needs to be changed from UEFI to BIOS (Legacy ROMs are always Enabled for these models).
All Remaining Dells only have a Legacy BIOS.
You need to use a Dell Windows XP Reinstallation ISO with Service Pack 3 that contains the storage controllers for these models.
Creating a Bootable USB
With this ISO you may use Rufus to check the ISO checksum and to create a Bootable USB:
Rufus does not need to be installed and can be run directly by double clicking on the application.
Accept the User Account Control:
There’s no need to check for Updates for Rufus. Select No:
Load the Windows XP Reinstallation ISO:
Press the tick box to check the Installation ISO Checksums:
The Checksums should match the following:
If they do not, then your Download is corrupt and you should try again. You can now press OK.
All data on your USB flash drive will be deleted. Select OK:
Rufus will now make the Bootable USB:
When it’s done it will say Ready:
Booting from the Reinstallation USB
Hold F12 while powering up your computer (at the Dell BIOS screen).
Select boot from CD/DVD or from USB respectively.
Press any key when prompted such as “h” when it says Press any Key to boot from CD/DVD.
This will begin the Windows setup. The first screen of the setup will prompt you to press F6 if you need to install a SATA driver from a floppy diskette. This screen flashes in a couple of seconds, if you miss it you will have to press F3 (2 screens down) and start again.
If you need SATA drivers its recommended to slipstream them and make up to date installation media as instructed here which prevents the need to use a floppy disc.
This screen also quickly flashes, you can just ignore it.
When you get this screen press Enter, you do not want to repair.
You then get the EULA, read it and then press F8 to agree and continue with the setup.
This will take you to this screen.
Press [esc] and continue with a clean install.
The next screen is important. Here you may create a partition, or delete any existing partitions. The way you do this is optional.
However it is recommended to delete all partitions on your largest disc by pressing [d] and [enter]. Then create a single partition on the unpartitioned space by pressing [c]. Select the default size (the maximum size) and then press [Enter].
Note if you are installing from a USB flash Drive. It will show as a separate disc, ensure that you don’t delete it.
Press [c] to continue the setup
Its recommended to do a full NTFS format.
Press [f] to format.
The setup will now begin to format the disk
Once the disc has been formatted Windows will begin to copy files to the partition.
The setup will copy all the files and then reboot the computer. The computer will restart and the setup will continue.
You will be asked to input your Regional and Language options (U.S. and U.S. English is usually default).
Select customise and change to your own preferences (I have selected English U.K.).
Click OK and then select details to ensure the keyboard is also set to your desired keyboard layout.
Select the correct layout from the list.
Select OK and finally change the top from U.S. to your personal preference (or the American Keyboard layout will still selected).
Select OK. In the next screen enter your name and organisation.
Note for non-Dell or Retail Media you will likely have to input a product key. For Dell media a SLP product key will be automatically input and product activation will be sorted out if a valid Dell BIOS is detected.
Enter the computer name and administrator password (optional).
Select your time zone, again mines is set to that of the U.K.
You will then be asked for network settings, choose typical unless you want to configure everything yourself.
Choose a Workgroup, just make one up of your own and put all your home computers on it or choose a Domain if you have a large organisation.
Wait for the setup to finish.
Click okay to change the screen resolution.
Select OK again.
Don’t worry if it looks bad, likely the Video drivers aren’t installed yet. The setup is almost finished.
Here the Welcome to Windows XP Theme starts playing (unfortunately most people don’t hear it as the sound drivers aren’t installed at this point…). Click next.
You will be asked for network settings, most people won’t have their network drivers installed during installation so its pointless and I recommend just selecting skip.
Register with Microsoft if you wish but theres no point for an OS that has reached End of Life,
Enter all the usernames and then select next.
This takes you to the final screen of the setup. Click Finish.
It should then reboot and you should be taken to the Windows Desktop.
For Windows XP Media Centre Edition there will be a few additional steps. It will automatically reboot and then install the Media Centre Edition programs, you shouldn’t touch your computer at this point. It should then reboot and you should be taken to the Windows Desktop.