Today, after leaving it downloading and installing updates all night, I deleted the old partion on the old 50GiB HD and removed it from my computer. Now my new HD will not boot up. I can see it in BIOS and have changed the boot priority, so that it is set to boot from the HDD first and not to boot from CD/DVD at all. This does not fix the problem. If I remove the CD from the drive, the computer throws a tantrum until it is put back in. Going back to the Windows disk, and opting to do a repair, the new drive will not show up. If I go to the installation screen, the new drive is still there, showing that it still has the partition and data on it.
The Windows disk is legit, for those who may ask, and I have used it successfully with two other similar HDDs. I don't think that's the problem >_<
Any help would be much appreciated - I'm tearing my hair out here!