Beos 5 To Be Released For Free
Be, Inc. will release BeOS 5 for free download later this quarter (no earlier than March 31). The free download (estimated at between 40 and 60MB right now) will only be available to individuals for personal, non-commercial use. Commercial use will require a separate license.
It appears to be primarily targeted at MSWindows machines, and does not require re-partitioning (which was an issue if you've ever tried it, especially with 3.0) to install. In fact, it appears as a standard executable which you can launch from within Windows that will exit from Windows and boot into BeOS. It can also run without a Windows installation as well. Also of note, the free version will include all the development tools currently bundled with BeOS.
Read the BeOS 5 Information FAQ
They also have a hardware compatibility list
posted to tell you which types of computers will best support it. As of now, G3 and higher Macs will not support it, but Intel-based machines, especially newer ones, should be ok.