After having installed every iteration of Elements since it was first rolled out, I should know that the install was set up by a very competent person for whom English is a second language. It's always an adventure to guess which word they've chosen in the new versions to ID the installer.

In the case of PSE 8 for Mac the following is the sequence that will save you Excedrin headache number 3765.

Double click on the CD icon

It's really a good idea to read the readme, though it doesn't give you a clue of how to proceed, it does warn you of possible problems after installation.

Double click on the PSE icon

Double click on "Setup" (that's the synonym in Adobespeak) in PSE 8 for "install"

After installing and doing a restart, be sure to use Bridge CS4 and PSE8. Any old versions will remain and trying to use CS3 with PSE8 can be confusing to say the least. That part was my fault. The install confusion is just because they don't hire someone as a proofreader who speaks English as a first language.