On decent videocards performance is good and roughly 80% of the Windows performance. I fear that your GPU is too light to run it well. A 6200LE is a very, very weak GPU (and that's paired with a fast core2duo..). I would upgrade to a more modern card, for about 40-50 euro / usd lets say a 9600gt or a gt220. Such a lowend card would already be 5x faster than what you have now and it would also support VDPAU for HD playback.
