New 16.04 on PowerPC G5


I’m new here, and i just installed Ubuntu 16.04 on my PowerMac G5 2,2 because Apple no longer supports this machine. Anyway, I’m wondering if it is safe to install X11 and MATE. My video card is an ATI Radeon X800 XT, which is an AGP 256MB. So, which driver should I use, and what are the expected results?