[Ham-Mac] Why Partition vs. Erase a SATA hard drive?

[Dick Kriss, AA5VU]

I just installed a Serial ATA/PCI-M card from SIIG that lets me mount one of
the new faster (cheaper) Serial ATA drives.  The card seems to work okay
and the new Seagate SATA drive seems fast.

The docs that came with card said to use the OSX Disk Utility "Partition"
option.  I may have screwed up by using the "Erase" option.  Anyone know the
difference between Erase and Partition.  The Partition has the option to
only make one partition.  I have never partitioned anything.

Dick AA5VU