Computer will boot the HD in port0 that is defult. If you already set the primary boot in the BIOS, it works fine and you don't need do something.
If you like you can change the 750gb to the port0, in case later when you have some problem need reset the COMS. In that case if you forget reset the boot order in the BIOS, computer will not boot into the 750gb instead boot into the 1TB.
So it is up to you.