Thank you. I know the serial was correct because I copied and pasted from a text document where I had it stored. I got it working further this morning (after a reboot -I had previously run the microsoft install cleaner to remove the previous version as it was giving an error about another version being installed when I tried to remove it via control panel.). This time it asked if I was upgrading or repair/new install. It accepted my serial on the new install, so I guess before it was expecting an upgrade key. But it did still error later on about not having permission to write the serial key.
"Error 1402. Could not open key: UNKOWN\Components\" with a lot of numbers and letters. "Verify that you have sufficent access to that key".
I am on windows 8 64 bit which has worked on a previous install. I can only guess the uninstaller has left things in a bad state now.