I now ordered a complete mediacenter pc as you see on this link: http://www.pcp.ch/PCP-CH-MediaCenter-Fusion-1a41022221.htm
I will install LinuxMCE on this system and will report back if the problems are solved. The pc I used to test the LinuxMCE is allready formatted, but I remember that I turned on the deinterlace function. Does this function maybe caused the vertical sync problem?
To answer your question, I like the Z5 very much. The picture I get is huge and the contrast is good and with this model I get two HDMI inputs, which I will use with my new mediacenter pc. I hope that the HDMI output of the graphic card will work.