I have the free 0.72RC1 running on my Toshiba G900 that too has 480x800. And this is no problem, running all very smooth. I am waiting for my x1, but I am sure, this TCPMP-version will work as good on the X1.
What one has to do is to try the video settings. On my G900 I use the "GDI" but this is depending on the PPC and can be different on X1.
Even largest .avi are played very smooth.