Thank you so much szaboaz for your reply. The issue was in fact a bad DVD drive. I should have checked that first before bothering you kind people
Happy New Year!
Does it boot the Windows 7 DVD, when the old hard drive is in?
Is there another computer around where you could try to boot it?
Maybe the dvd disk is faulty, or the writing process went wrong (that is if you created the DVD from iso image). In that case you should do a checksum-check on the iso image, and write it again, maybe with reduced speed.