I have a mac and when go to install Limewire, it downloads the installer, but wont launch and download it!?

Answer 1

You're not clear on what part of the process you're stuck on. After you download it and it appears on your desktop (or alternate download location), double click the .dmg file and then double click the installer that opens up to open it. Follow the instructions and then it's installed. If you have a problem with that process, then you may have more serious issues.