Only showing 500mb

SOURCE: How to format the LaCie 500GB d2 Quadra for Windows XP??

This way it should work...
Connect your drive to the computer...
Go to: Start > Control Panel > Administrative Tools > Computer management.
A new window will appear...
Select Storage > Disk management on the left of the window.
Now you will see the different drives that are connected or part of your system.
One of the drives listed there is your LaCie, i think you'll recognize it by name...
Right-click on it, and select 'format'
In the new window, select the new volume label (as you like it), the file system (use NTFS), and set allocation unit size to default.
Make sure 'Perform a quick format' is not checked...

Then click OK. Your drive will be formatted now... Don't interrupt the process