We've experienced problems installing DP onto very large hard drives (commonly 80gig 120gig, etc) , like the 80 gigabyte drive that comes in the G4 with the dual 800 processor. Usually, while attempting to install DP, an error appears that says that the necessary space is not available.
MOTU has documented this as a problem with the VISE installer software. The issue is being addressed. A solution should be available soon.

Here's what you can do to fix the problem:

1. When you get to the EASY INSTALL screen. Click on "Easy Install" and switch it to "Custom Install". Click the triangle next to Digital Performer, and place an "X" in the box next to every item below DP -EXCEPT- for "Extras".
Allow the installation to complete and restart the computer. If you wish to install "Extras" later, simply do another "Custom Install", this time choosing only "Extras".

-OR-

2. Partition the drive into two 40 gigabyte partitions.