Western digital drives have two different sets of jumpersettings. (Master if single drive) and (master if slave attached). You will need to make a partition big enough to store an image on the seagate, make youir image in the partition, switch drives putting the seagate as slave and the WD as master with the proper settings, boot from floppy or CD with imaging program on it, and restore to the WD. Pay attention to drive and partition sizes so you don't get confused as to what is what when in dos or command interface.
I use Drive Image 6 for these jobs but it ain't free.
http://www.seagate.com/support/kb/disc/ ... tings.html
http://www.seagate.com/support/kb/disc/ ... shoot.html