For details on setting jumpers on IDE (PATA) drives, see my post dated today (11-05-2009) in this thread:
http://www.tomshardware.com/forum/273978-31-settings-installed-drives
It is focused on a person who had IDE drives and needs to move them from
external to internal connections.
BEFORE you do all that reading, answer this: are ANY of your drives IDE (PATA)? Because with SATA drives (and you say BOTH of your new drives are) THERE IS NO MASTER TO SLAVE!
So without any doubt, you do NOT set Master or Slave on the two new SATA drives, and you probably do not want to change any jumpers they have.
The older 1TB drive you have MAY be on an IDE port as the Master (set by jumpers) of THAT PORT ONLY, or it MAY be a SATA drive, too which in fact is NOT a Master of anything.
What I suspect you mean is that you have an existing 1TB drive (probably SATA, but does not matter) that is your BOOT DRIVE called C:. In your Bios Setup screens it should be set in the Boot Priority Sequence as the device to boot from (maybe second choice after your optical drive). That make it your BOOT drive, not your Master drive. From there you want to add two new SATA drives on their own ports. Unless you specifically Partition one or both as Bootable Drives and install some Operating System on it (them), both will simply be drives to used for data. Neither will be Master of anything.
On SATA drives, unlike IDE's, any jumpers present are NOT used for Master, Slave, etc - there is no such thing for SATA. There ARE jumpers on some SATA drives (I thnk WD inits have them) for other purposes. One jumper is used for uncommon cases where you need to force a newer SATA II drive to slow down for compatibility with an older SATA controller. If you KNOW your controller is also SATA II, you can set that jumper to run at full SATA II speed. Most other jumpers are things you do NOT want to change, so leave them alone.