Why not?
I thought the only way to get DD5.1 output was to use the Advanced SCART Lead (official or 3rd party), which is *also* an
RGB enabled SCART lead. (the standard SCART you get with an XBox just uses composite video)
(so what do you mean when you say you swapped from your SCART lead to an RGB connection?)
Also, out of interest, what settings did you change on the TV to get it working again?
XBox Media Player (& Centre) can be installed on its own. It's a matter of getting it from "the usual sources", & then just FTPing it over to the XBox (& also editing the config xml file for your particular setup).