If you want OS4.1 or MorphOS 2.x (and soon 3.0) releases, you should get the systems that are designed better for these like Macs and SAM's. For using both in one machine you can try searching for a Pegasos system.
Good luck with your search.
Actually, it is a Pegasos2 that is supported by MorphOS2.x and OS4.x, not the original Pegasos systems. I am sure that is what mfilos meant to type.
I must agree with him, that if you are considering running OS4.x, and/or MorphOS2.x (and soon 3.0), buy a Pegasos2 for running them both, or buy one of the other more modern supported hardware choices, instead of trying to find the ultra rare G-Rex cards, that are getting quite old, and enjoy the better performance of a G4, or at least the SAM460ex's 1.15GHz SOC processor (I think that is the correct clock rate of the 460ex?), instead of a maximum of a 233MHz 604e (unless modified by Stachu to a maximum of 366MHz). You will be happier with the increased performance and RAM capacity, and probably spend less money and have less headaches.