Converting MyPassport from PC dedicated to MAC dedicated

I would like to permanently relocate MyPassport Elite 500GB, USB 2.0 from:

-  a Windows 7 based PC support to

-  an iMac G5 with Mac OS X 10.5

I have no intention of shared platform usage.

First - Is it possible to make this conversion and end up with the functional equivalent of having purchased a Passport for MAC?

Second - If it is, what is the process?  Do I need to purchase/download any support software?

Check your other post.