I was given an Xbox with unleashed x already modded to it. I would like to take it off or write over it and install XMBC. Is there a guide to do this?

Unleashed X Version 0.30.0515A Build 565
Kernel Version 1.0.3838.1

Thanks,
Joseph

It's UnleashX.

How is your Xbox modded? If softmodded, which softmod?

It appears to be a softmod version. I've opened it up and I don't see a modchip anywhere. It's been so long since I have fooled around with an Xbox. My memory of things you can do to them is so weak now.

Auto-Installer Deluxe has XBMC on it.

I just replaced the UnleashX files on my HDD with the XBMC files, but that was because I couldn't get the Auto-Installer Deluxe method to work (trouble backing up EEPROM for some reason) and I've damn near bricked my Xbox twice using this method. So it isn't recommended.

AID is designed for chipped boxes, not softmodded ones. It does work on Xboxes softmodded with SID, but you need to know what you are doing. As you have found, it isn't guaranteed to work.

Replacing UnleashX with XBMC is cleaner if you use the shortcut method. Put XBMC in E:\Apps\XBMC\, and put the shortcut files in place of your original dash.