My dad had received an old PIII computer which he wants to use as an internet computer. I figured linux is the best option.
Problem is, It cannot be booted from anything other than the hard drive, the BIOS looks blocked from all the boot features.

I was wandering if it was a good idea to connect the hard drive to a different computer and install linux from there, then putting it back.

My question is whether it will mess up the linux setup? Installing it with one set of hardware and then putting it in a totally different computer?

No, it should be OK, as long as you don't customise the kernel.

As well as that, I would copy the contents of the cd/dvd to the drive until it is connected to the web.

Then you will be able to grab any updates, and customise the kernel to make it smaller, if required.

Hope this helps, Glenn

Take the above idea one step further.
See if you can connect the drive into your computer and install a base system onto it. Remove the drive and insert the rescue cd onto your computer and reinstall the boot loader.
Reconnect the drive to the older computer.
Be sure that you use the kernel compatible with each computer's architecture when doing an install.
Have you tried removing the battery to reset the BIOS or using a backdoor password?

Thank you both Installed vector linux succesfully

Cool!

Mark your thread as "SOLVED" to allow others to find it.

For the future, you may find it more convenient use a "Super Boot Manager" floppy. It's capable of booting off of CD drives on systems can only normally boot off of a floppy or hard disk.