You need a driver for ths disks - you can download one from the DELL web site - which one you need will depend on you configuration, some DELL 390s use a SCSI controller that can be conigured to use RAID0 or RAID1 - each has its woem driver, some 309s use SATA disks - gain a differnent driver. You need either to
a) Press F8 and provide the correct driver on a floppy disk (if you have one)
or
b) burn a copy of the Windows CD and include the driver on it