Seems as though you have tried to restore the machine to factory condition? Try it with this method:http://en.community.dell.com/support-forums/laptop/f/3518/p/19393623/19919103.aspx
If you wipe the drive, you may have to phone MS to reactivate the product.
This may help prepare your HD.
(Note that by using this utility you will lose any and all data on the disk with focus)
Clean all and formatting takes quite some time (this command line usually takes about 2 1/2-3 hours on a 250GB HDD), so be patient if you decide to implement this. Progress is only noted by a blinking cursor "_". We are not going for the "quick" cleaning or formatting.
To access diskpart boot from install media. Select Next. Select Repair Your Computer. Select Command Prompt.
Hit the ENTER key after each command.
LIST DISK (Generates a list of disks available)
SELECT DISK # ("#" will indicate the actual disk number where Windows will be Installed)
CLEAN ALL (Completely wipes disk and writes zeros to it)
CREATE PARTITION PRIMARY (Creates a primary partition)
SELECT PARTITION 1 (Directs focus to newly created partition)
ACTIVE (Marks partition as active)
FORMAT (Formats the partition-if no format is chosen the default format will be evoked)
ASSIGN (Assigns a drive letter to selected partition)
After cleaning all possible data on the disk to house Windows, boot from .ISO and select Custom install (or the equivalent thereof).
When you get to the screen asking where to install Windows, select the partition created during diskpart. In the bottom panel select Delete. Then select New. (This will let Windows install the 100MB partition System Reserved_Active).
If you need further assistance with this,keep the thread updated.