macbk not recognizing ext. hard drive

[laf]

i searched for my problem and didn't find it, so apologies if this has been covered somewhere on this site. if it has, please direct me to the page/thread.

i just bought a new macbook (leopard), and i tried to connect my old hard drive to it, via usb port. i had the hard drive from my old mac (tiger) removed and purchased a case and cord for it. i have since used the hard drive on a leopard imac, which recognizes the hard drive immediately. when i connect it to my new macbook, it doesn't appear in the finder, nor on the desktop.

please help me access my hard drive.

thank you,
lucy