Ok first problem here.
You can't use boXplorer to rip a retail dvd to the xbox's hard drive. You would need a proper ripper that can decrypt dvd's. If you want to rip on a pc and then ftp the files over that can be done. We may in the future see Avalaunch have the capability to decrpyt dvd's but that won't be for a while yet.
Second problem.
Full dvd support is being worked on for xbmp in fact it's gotten quite far. You can navigate to the dvd in xbmp and launch video_ts, this will run the dvd with menu support. However they've just gotten this working so still plenty of bugs, menu highlighting doesn't work etc. Also from what I hear you can only do this from the dvd drive not the hard drive. I expect this will be fixed.
There hasn't been much done recently with xbmp but that was cos the devs took a holiday over easter so I expect we'll see lots of work being done on dvd support soon.