Re83L
Expert Member
I don't have a proliant microserver, but I was able to get my ATI HD5450 working in Kubuntu simply by installing the additional drivers provided in the menus. Once I rebooted, everything worked and I was able to watch Avatar in 1080p via XBMC on my 40 inch LCD over HDMI.
What exact versions Kubuntu are you using?
What release of XBMC are you working with?
What processor do you have? Are you sure it's not just your processor that's powerful enough to handle the decoding?