I have a pc in my living room that is turned on all the time. It has two uses:

1. It is my fileserver
2. It is my media pc

It is running Vista at the moment, the reason is that under Vista I can play HD movies (x264 files) using GPU acceleration. However, I read that GPU acceleration can be done under Linux too, using XBMC. I didn't do much research yet but I am under impression that there is a Linux software called Myth TV that can do GPU acceleration as well. It seems I can download Myth TV and run it on Linux (I would use Ubuntu) or I can download Mythbuntu distro.

Can anybody advice which would be better? I am familiar with Ubuntu, I run it on virtual pc in Windows 7 for secure browsing. I believe that Mythbuntu has lower footprint because it doesn't have apps like Office suite and email etc and I like that, I don't need my pc to do anything other than 2 things I mentioned before. More robust and reliable the better.

Or maybe running XMBC or Xine under Ubuntu is another option, given it can do GPU acceleration...
Btw, I don't need TV capability or music, I only watch movies...

Specs of the pc just in case:
C2D E6750 @ 2.66
8gb of ram
Nvidia 9500GT
Asus Maximus board with on board sound (I hope the sound will work, I have never tried it)