How to make 2 Hard drives act like 1

[jambab]

I am going to take the hard drive out of my old computer which is 250gb, and i got 160gb atm in my computer (desktop) so i want to be able to install the hard drive and then assigned it so it both of them act like one?

im not bothered about formatting/imaging because i know how to do that i just want to know whether its possible and how to do it.

 

[kmote]

You have two options RAID and JBOD depending on your drive controller. In order to make use of all the space available you probably want JBOD.

 

[jambab]

ok, and how do i set up the JBOD?