You have to enter the BIOS to change the boot order to CD drive first.  If you stick the intallation CD in the drive and then reboot the system, hit F2 as soon as the machine starts to boot -- if you look up at the right corner of the screen you'll see the options for F2 and F11--F2 will give you a one-time boot option.  Make the CD drive the first boot device and the machine should then boot from the CD so you can do the installation of Windows. 

 

Make sure you have either your Dell Resource CD or fresh downloads of all your hardware drivers and system software.  Install the Intel Chipset driver first.  This is critical.  The other drivers like audio, video and modem can be installed in any order.  Also make sure to install the Dell Desktop System Software.

Thanks for the reply.I have tried to boot from cd and floppy ..yes I changed bios and nothing works.I have installed several computers in the past and have never run into this problem.in bios it is showing the cd/dvd drives,showing the hard drive too.I am hoping that it is not the mobo(controller)Thanks alot for the help anyways.Any other ideas woud be greatly appreciated..Thanks !

Unless the battery is new I would replace it.  Lithium cells generally last from four to seven years, but they can fail sooner and the D2400s are among the older systems now.  I've seen Dells do funny things with a bad battery; one of mine forgot that it had a floppy disk drive.