gbaka,
never tried or even heard of the sony version but as with the ATI media centre hardware manufacturers should stick to developing hardware as apposed to software.
Windows Media Centre Edition 2004 is XP Pro with a Media Centre add on, it's nice to look at and generally runs very well, the idea behind it is that you stick a SFF (small form factor) pc under your tv in your living room and use it to navigate through stored and internet based media, it's also designed to input annalogue/digital television which will enable the user to pause live tv, record and then playback all from a simple menu structure.
Although Windows Media Centre runs on an XP Pro platform i wouldn't even consider using this software without at least 1024MB RAM, a top end processor and at least a 9800 pro, but that brings us to a problem with the SFF pc's, small space lot's of high power componants it's gonna get pretty hot, (i've seen them where you could almost fry an egg on the chassis!), for example you can forget a P4 3Ghz + as this will run very hot. and any graphics card that's larger than normal, eg, Nvidia FX 5950 will take the space of your one and only PCI slot.
went a little bit off the subject there, but hey! hopefully useful to someone
James