...PC!? Hello, I have two Hardisk in my computer in one of them is winsdows XP which is primary Hardisk and in the second one is Linux fedro, I installed the linux completely even it said it's successfuly installed but when I rebot it goes direcly to the windos my question is how to go to the linux? I put the secondry hardisk to the primary and remove the hardisk which has the windows XP but it gives an error that NTLDR is missing, what could be the problem, even though I installed the linux fedora 4 with no error .please help me I am new at linux I just know how to install it that is all, could please help me in this issue?

Your PC lacks the linux boot code!!

If you swap hard disks, only got an error, uh?
That's the evidence. Your linux installation lacks the booting code. You must setup a bootloader : LiLo or Grub .
You may review the Fedora setup steps, visiting http://www.mjmwired.net/resources/mjm-fedora-fc4.html .

If you correctly setup a linux bootloader, you should be able to boot Windows also.