Powerbook g4 - la cie 500gb doesn't mount.

No, but why not ask La Cie? They have pretty good support, and if your computer isn't recognizing it, you can feed them all the information they need by downloading a freeware program called Balarc advisor, which not only tells you everything in your computer, with model numbers for hardware and all of your software (with their unique codes), but will also inform you if you are missing any needed Windows updates. Once you know what you have, go to
http://www.lacie.com/support/faq/faq.htm?faqid=10338 You may need to download something from them for your poswerbook different from your g5..

Either your HD is broken or you this is the first time you install a new HD... and there are some details like what kinda cable youre using and if that HD is jumped correctly... so, just in case you feel a little clueless:

1. Make sure your G4 supports that exact HD by calling MAC.
2. Make sure you have the right data cable (one that allows you to use it at its full transference speed and of course that is supported by the motherboard, all things that MAC will tell you).
3. Make sure your HD is jumped the right way, many HDs comes without a jumper but it does not means that they are not necessary in any case. (To jump it right see instruction manual on HD company`s website. If you are clueless in this part, call the HD`s company, phone or chat is always better.
4. If everything above is right you just have to get Partition Magic or Paragon Partition Manager, out of the Internet (just look for it, its very popular and simple), burn it inside a CD and boot up with it. (in case you ve never done a thing like that, just take any bootable CD you have or can find, and add this PM or PPM program to the CD,... of course in a new copy of that bootable CD, with the additional PM inside and once you boot, you will be able to path to that folder and run the program...) Partition Magic comes for windows too... so you will not need to boot from any CD.

IMPORTANT: if you cannot find PM or PPM for MAC you will need a PC with windows inside...

if you are sure you have no problems nor lack of stuff just run partition magic and do anything you need with the HD, latests versions also have a way to partition for OS systems...

in any case, if your system or motherboard cannot detect the full HD space, try "cheating" by just using the space you can for installing and then format the rest of the HD with PM or PM from windows or DOS.

In the worst case... use the HD that comes with the G4 if you have it, otherwise buy a little one that does not have that problem and install OS in it. Then just get a external case for your big HD connect it to the mac by USB or Firewire and use it for DATA storage, IT IS ALWAYS BETTER to separate system from data.

and next time remember, MAC is great to work but not to upgrade it...

Good Luck