Dell Precision T5400 (Late 2007) - Manual (Page 150)

150 Reinstalling Software
NOTE: If you wait too long and the operating system logo appears, continue
to wait until you see the Microsoft ® Windows ® desktop; then, shut down your
computer and try again.
NOTE: The next steps change the boot sequence for one time only. On the
next start-up, the computer boots according to the devices specified in the
system setup program.
5 When the boot device list appears, highlight CD/DVD/CD-RW Drive
and press <Enter>.
6 Press any key to Boot from CD-ROM.
7 Follow the instructions on the screen to complete the installation.