I have an old Windows computer that won't boot (missing NTLDR or something??). I don't even remember what Windows OS was on it. Anyway, what I want to do is this: forget Windows and install ubuntu on this computer and then possibly sell it as a fully functional machine. Can I download ubuntu onto a set of cd's or dvd's, using this Vista pc, then take the downloaded media to the broken machine and install ubuntu system from them? Will the downloaded system on the cd's be bootable? I have an old Win98 startup diskette that will boot to drive A: and that will let me change to drive D: (the cd drive). So if the downloaded ubuntu system on cd's or dvd's is bootable, can I proceed to install it from there?
First thing to do is check if your hardware can handle Ubuntu. For a list of system requirements Click Here and read the part that talks about requirements. But I can tell you from past experience that it will be fine to install Ubuntu.
1) Get Ubuntu Click Here
2) Burn The .ISO file that you downloaded into a CD.
3) Turn on the computer in question on.
3) Place the CD it in CD Drive of the the computer that you want to install Ubuntu on.
4) Go into the BIOS, and change the boot order to boot from CD.
5) Save and exit BIOS.
6) Ubuntu installation will start once the CD boots.
For more detailed or step-by-step instructions Click Here
"missing NTLDR" is a Windows error message (NTLDR is the small program that boots Windows NT). If your computer makes it to that error message, then it is booting properly and has no issues, it is just the windows install that's broken.
So, the computer is not "non-bootable". Depending on how old is "old", it may be unable to boot the installation media directly, in which case you can just use a floppy loaded with something like SmartBootManager, which is able to boot CDs itself (no matter whether the BIOS supports bootable CD's or not, SBM has its own implementation of El Torito (the bootable CD standard)).
You can use SBM if you have a floppy drive. I'm afraid the Windows 98 floppy won't be of much help here (there is probably some clever way to boot a live CD from MS-DOS, but it won't be as easy as just trying SBM).