Got past that, just did a repair on the previous attempted installation, so it's done that and rebooted - got the "installing windows page" where it tells you about a load of windows bollocks, 39mins to go etc, and now got a pop up "system error"

lsass.exe - system error : an invalid parameter was passed to a service or function

Then when you hit okay it just reboots

Can't continue now, gott go out in half an hour