HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Setup and substitute your hard disk path for the existing CD-ROM path. Next, navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion. In RegEdit's right pane, double-click SourcePath and enter the new path.
You should also check HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Setup and HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Setup\Installation Sources for a path to the CD-ROM drive. If the CD-ROM path appears in these keys, then change them to the hard disk path also.
Im not that smart..I stole it from
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