While attempting to upgrade XBMC on my Xbox I accidentally deleted something I shouldn't have causing the Xbox would only boot into the default dashboard, cutting me off from the hard drive through anything like FTP or another dashboard.
So how did I fix it?
I actually found this tutorial on -- of all places -- G4 TV's website.
After finding an ISO of Evox and burning it to DVD I was able to get XBMC back up and running. There were a couple of other things I learned though that might help some people out.
For instance, in order to take advantage of the upconverting capability of XBMC you have to enable the resolutions in the default Xbox dashboard as I found out here under Screen -> Resolution. I didn't know this.
Sadly, after I enabled Resolutions up to 1080i and changing the settings in XBMC settings to 1080i 16x9 I found that I couldn't really play any video files (standard xvid) over 350 megs. This was rather disconcerting. Luckily, I found this explanation about the memory limitations on the Xbox.
Sure enough, after limiting both the dashboard and the video settings to 720p 16x9 all the video files play flawlessly and look incredible, I can't believe I never knew the Xbox could upconvert my video files until now. I became a fan of upconvertion when we got an upconvert DVD player and hooked it up through the HDMI port. Upconverted DVD movies at 1080i look absolutely stunning and the video files upconverted from the Xbox don't look half-bad either. Isn't technology grand?