XPS 400 - Floppy disk seek failure

yes, i went there and chose boot to utility partition it still show me same eror. 

Try a diagnostic on the hard drive.  If the boot code has become corrupted the computer tries to find other devices that have boot code, such as the 3.5" diskette drive.  If you don't have a diskette drive, the computer may still try to find one if the hard drive becomes unavailable.  A failing hard drive is often the basic cause of the problem and you should test the drive  before going to the trouble of restoring the software.

If you have no diagnostic disk, and you are still using the hard drive that was delivered with the computer by Dell, you might be able to boot to the Utility partition and execute the diagnostic program found there.  Start the computer and press F12 while the self test is running and you still see the Dell logo on the display.  Choose to boot the Utility partition to find the diagnostic routines.

From your description I believe your hard drive has failed.  To be certain, however, you need to run a diagnostic test.  Dell has an iso file that can be used to make a bootable CD for your computer.  You will find that here:  XPS 400 Diagnostics.  You will need a CD burning application that can burn .iso files; the link to the diagnostics has instructions for use of the file.  Once you have the disk, boot from the CD and choose the tests for the hard disk drive.

i booted from the cd i ran over some test and it didn't give any error . And, when i reboot the computer, it still gives me a same error.

Restart your computer, press F2 during the Dell logo on the display to reach System Setup.  Navigate to the section on the SATA controller and let me know what it says; I believe most XPS 400 machines were shipped with the controller set to RAID On, but it is also possible to set it to RAID Autodetect/ATA.

When the BIOS completes the self test it attempts to hand off the boot process to the code located on the hard drive.  The fact you are reaching a blank screen with the cursor in the upper left says that the computer can't find code in the first sector of the drive that has been set as the boot device.  A failing hard drive is often the cause of this problem as the boot sectors become unreadable.  If you can't find any error report from the hard drive, however, you might have the SATA controller set to an incompatible setting, or the boot sectors have become corrupted.  As I stated above, most XPS machines were shipped with the SATA controller in RAID On.  If you find it in RAID Autodetect/ATA, try switching it to the RAID On setting and try booting the computer.

In Sata, the factory default setting is raid autodetec/ahci .also, i tried switching it into raid autodeyect/ata and raid on. It still gives me a floppy diskette flaiure. Seems like i need to reinstall my xp.

I'm afraid I agree.  One other thing you can try as a last resort, and that is to try tapping the F8 key just as the Dell logo disappears.  If the hard drive has any boot code whatever you should wind up in the Advanced Startup menu where you can try using the Last Known Good configuration to see if the machine will boot at all.  Also, you can try repairing your existing installation with your installation disk.  You might wind up in the Repair Console, or if your installation CD has the same service pack as your hard drive, you might be able to perform a repair installation.  Since your present situation appears to require a complete reinstallation anyway, I think these would be worth trying before wiping the hard drive and installing fresh.