Maybe so, but its much easier to get a smooth consistent frame rate on Windows and you find far fewer video files that have problems.

Its not uncommon for VDPAU to break on some files and certainly when you start trying to deinterlace 1080i files, its often really really hard to get it to work properly where on PowerDVD on Windows "it just works".

As I understand it though, because mplayer is heavily optimised for CPU playback they hit a big snag when dual-core came out, as mplayer is optimised for single-core CPUs. It relies on knowing exactly what is going on in the CPU cache which means no multi-threading, as you spread the load over multiple cores that way but cannot optimise to the same degree so it would have far far worse performance on single-core machines than it does now.

Its not that mplayer is bad by any means, its my preferred player on Linux, but its optimised to do things one way and as VDPAU is relatively new I think its still somewhat in catchup mode. I hear the latest development version now plays Blu-ray as long as its already been decoded/ripped to the HDD, so its certainly getting there. But there a lot more scope for things to go wrong than on Windows as things like VDPAU can break unexpected and without you realising what has happened, whereas on Windows if anything like that broke generally the whole system would stop working. Its both a blessing and a curse that Linux sometimes tried to go on even when something is not working quite right.