Your options are:
- Multi-channel (meaning your PC does the mixing and sends multiple channels to the surround receiver) analog
- 2-channel digital S/PDIF over Optical (TOSlink) or COAX, and passthrough of 2 channel encoded DTS or Dolby Digital if your driver, software player and surround sound receiver supports it
- Multi-channel HDMI - note, not all Audio HDMIs are created equal! Some audio HDMI drivers don’t support passthrough or multi-channel, (generally onboard [e.g. ATI 4250] video cards)
- ATI Scaling keeps resetting - Run ATI Catalyst Control Center (ccc) as Administrator to save settings or edit the registry and reboot
- (XBMC) Jerky or Stuttery Playback (if you’ve already checked the obvious) - I found that displaying video on a screen that’s not your primary desktop, in a ‘fullscreen window’ rather than ‘true fullscreen’, leads to annoying jerky playback. Either make your playback screen the primary, or enable ‘true fullscreen’. I found I also had to enable 'true fullscreen' to resolve a slow / stuttery playback issue.
- When in 'true' full screen, it turns out some processes, namely ATI Catalyst Control Center, cause XBMC to minimise/lose focus. Fix this by stopping the applications from running (e.g. at startup). If you’re adjusting gamma / colour correction with it, use the built-in Windows colour correction instead.
In order to get better remote control (e.g. the green Media Center button launching XBMC) I followed this (somewhat overcomplicated) guide.