What does initializing have to do with formatting? Initializing updates
the partition table along with saving a disk signature (part of the MBR;
see
http://en.wikipedia.org/wiki/Master_boot_record) that gets also
saved in the registry (to track the disk regardless of how it gets moved
around rather than use the old BIOS scheme for detection order in
assigning drive letters) along with defining whether you are
adding/extending a basic or dynamic volume using that hard disk.
Initializing takes only a few seconds. Now you'll have to format the
partitions (after you create them) on the newly added hard disk.
http://www.simplyguides.net/guides/prepare_second_hdd/prepare_second_hdd1.shtml
To prepare a hard disk drive involves the following...
‧ Initialize
‧ Create A Partition
‧ Format A Partition
Since the disk has already been initialized because it is a used disk
from another Windows host, there isn't much to initialize. At this
point, the only time you'll probably see some initializing is if you
change between using basic and dynamic volumes. Initializing an already
initialized disk does do much (I think the disk signature might be
updated but perhaps only if a conflict is found with another volume that
already has the same signature).
You did not install a new hard disk (that needs initializing). You
installed a *used* hard disk that was already initialized.