A lot of places will replace broken stuff with old or returned stuff, I am suprised IBM did it on the simple fact that they probably sent you another 75gxp which means you will be sending it back soon .
IBM has been replacing the 45GB 75gxp with new 60GB 60gxp because they stopped with the 75gxp line, but who knows what they are thinking.
And when they said installed drive, where they talking about you buying a computer from dell or another pc company like that with the hd in it?