The development of external USB storage devices has made it possible for computers to install an operating system (OS) even without a working CD drive or floppy disk drive. You can install Windows XP to a Dell OptiPlex SX260 from a USB flash drive. WinToFlash and FlashBoot can transfer the files on the OS CD to a USB device. You can then boot from the USB drive and install the OS to the OptiPlex SX260 just as you would from a CD-ROM.
Download and run WinToFlash. Connect to the computer a USB flash drive at least 2 GB in size.
Click the "Task" tab. Select "Transfer Windows XP/2003 Setup to Flash" from the drop-down menu. Click "Create." Click "Next."
Insert the Windows XP OS CD into the CD drive. Click "Select" next to "Windows Files Path" and choose the drive letter assigned to the CD- or DVD-ROM drive.
Click "Select" next to "USB Drive" and choose the drive letter assigned to the USB flash drive. Click "Next" to create a bootable copy of Windows XP on the USB drive.
Remove the flash drive from the computer when the process is complete. Connect the flash drive to the Dell OptiPlex SX260.
Download, install and run FlashBoot. Click "Next." Click "CD -> USB" on the "FlashBoot Main Menu" screen. Connect a 2 GB or larger USB flash drive to the PC.
Insert the Windows XP OS CD. Click the radio button next to "CD/DVD Disk" and select the correct drive letter from the drop-down menu. Click "Next."
Click "Convert Windows XP/2000 Installation CD." Click "Next." Click the radio button next to "USB Device." Select the flash disk from the drop-down menu. Click "Next."
Click "Next." Click "Format Now." Click "OK" when the process is complete. Remove the USB flash drive and connect it to the Dell OptiPlex SX260.
Turn on the Dell OptiPlex SX260. Press "F12" on the boot screen to open the boot menu.
Choose "USB Flash Device" from the options and press "Enter" to boot to OS set-up.
Follow the on-screen directions to install Windows XP to the Dell OptiPlex SX260.
You'll need to use another computer with a working CD or DVD drive to create the USB flash drive.
The above steps will format the files on the USB drive. Move any files on the drive to another storage device before proceeding. Don't move the files to the Dell hard drive, since the contents of the drive will be erased when the OS is installed.