MSDash, the Dashboard that comes stock with the XBox...the first time you turned on the XBox after you bought it, before it was modded, it went to the MSDash, and you go to Memory-Game Saves I believe. Just load up your Stock BIOS and it will boot to it.
Delete the XML as well, use the one that came with the XBMC you installed, and edit that XML to reflect any changes you need.