I do not know from where you can dl a complete OS ..
Your problem is that the BIOS cannot find an MBR - is your hd reported in BIOS? Then it could be a problem on the hd... the MBR, for example.
You can get an XP/2000 Recovery Console from this link: http://www.thecomputerparamedic.com/files/rc.iso
The console runs from the cd so you don't need an OS cd or any files from your C drive to use it. I know it works. All you need is an image burner like Nero 6, CD Writer...
Tips... take the iso and then BURN THE IMAGE. Do not use Data CD or any other mode cos all you will get is a copy of the iso [which you have already...and your new CD will not be bootable]; if you look at the files on your new cd and see .iso mentioned anywhere, start over. If you use Nero 6 then the defaults for image burning are fine, skip the silly advice that you may find on the web. You merely select Burn an Image, browse to and select the .iso and press Burn. That is all it takes. Burn it to a CD-RW if you wish; there is no need to close/finalise the CD whether it is a RW or R. Multisession works fine. If you use a CD-RW then hold the burn speed lowish, say 4x.
Run chkdsk to perform a simple check of the drive. If there are any errors reported you must then do chkdsk /p to attempt to recover them, and follow with chkdsk to see if it is fixed. If not, try /p again, and so on [chkdsk with no parameter will not fix a thing]. You can just run chkdsk /p immediately if you wish.
Try then the command fixmbr.