I am having some issues with my hard disk on my laptop so I am changing it. Hence, I will not have any OS when I change the hard disk. (I can't re-install Windows, as I have the Installation CD broken). I would like to know if I can install Ubuntu as the first OS in a laptop which doesn't have any OS on its own?
Yes, you can.
Simply install Ubuntu from a USB Flash drive or a DVD. But you would need another computer to make a bootable flash disk or to burn the DVD.
If you want to create the bootable flash drive from Windows you can use one of these tools:
Actually, there are a lot more.
Also, keep in mind that installing Windows after Ubuntu will overwrite Ubuntu Bootloader, but you can always restore it.
Yes, of course you can. You can install any OS as the first (and only) OS, Ubuntu is no different.
Just boot from an Ubuntu CD and install normally. You might have problems if you later install Windows and that overwrites Ubuntu's boot loader (
grub2) but that it a completely different issue. If you do eventually run into this problem you can fix it by reinstalling
grub as described here: