Quote Originally Posted by metallic View Post
Because according to the OP, space is at a premium. As long as you check "Preserve User and Network Settings" during the install, all your personal files will be copied back to the right spot anyway. All that leaves is the old system files which are a waste of space at this point.
But he is getting a new disk so space is no longer at a premium.

The old system folder is not wasted space until you are sure 100% of your applications are working OK and everything is OK... Even then I would wait a month to make sure you have not forgotten something. Much easier to fix broken applications that are missing some file in the system area when you have the old one around rather than futzing with backups or other disks.