You have your Windows DVD so is there more to this story?
To head off an old discussion, those OEM installs DIE WITH THE MACHINE. Read http://news.softpedia.com/news/Microsoft-The-Windows-OEM-License-Dies-with-Its-Computer-88220.shtml
So I'm looking to build a new PC, but I already have a good 1TB HDD and optical drive.
If I use the current HDD (already has windows 7 on it), and just plug it in, will it work properly? Or do I need to format it and buy Windows again? (Really I'm just trying to avoid buying Windows AGAIN.)