The old one died... the cooling fan of the video card broken.
The new one is running 32-bit version of Windows Vista Home Premium with SP1. Also tried some features that I had never used before, like putting recordings onto DVDs.
The setup experience this time is pretty good, Vista SP1 automatically recognise my WinTV-Huppauge PVR-150 MCE and the USB IR receiver (for MCE remote "beanbag" in the kit). Everything is plug and play.