if the hard drives are on different channels, you can
get a boost. it's sort of like software raid. put directories
that will be accessed or written to at the same time on
different drives, as long as both drives are about the
you can test this.
time how long it takes to copy a 1 gig file to another
place on the drive, and how long it takes to copy it to
the other drive. that way you can see the difference.