Alright, this is something simple really.
Your battery will become inoperable after you convert it to a Pandora's Battery. It will just turn the system on and leave it at a blank screen, so either way, you're gonna have to buy a new battery.
If you have a spare lying around, good, but you will need some good welding skills. To make a Pandora's Battery, you need to melt a peice of metal in the battery, which if done incorrectly, will blow the place sky high.
If you're not good with welding, just buy a Pandora's Battery online. You figure that if you're gonna buy a new battery anyways, you might as well keep your current battery.
To make a Magic Stick, you need to download a program that will convert the data of the Memory Stick Pro Duo so the Pandora's Battery will detect it. It can be found readily at http://forums.afterdawn.com/thread_view.... . Just follow the instructions down to the letter, and you'll be fine. Whether or not the program will work for you is questionable, since you're running a Mac, but it's worth a shot anyways.
If you just wanted to simplify things, I suggest buying a battery from http://www.pandorasales.com . They're $7.99, excluding shipping, and they send you idiot-proof instructions. You can also buy a bigger memory stick, since 2GB won't hold a lot of games.
I bought my 8GB Memory Stick and Battery from there. Definitely reliable.