I postefd a while ago about how to get my Ubuntu machine successfully resolving Windows machine names when I don’t have a DNS server (i.e. put WINS in the /etc/nsswitch.conf file). It truns out that this is the only thing that was stopping XBMC from running my machine. Once I removed that, XBMC runs just fine!
Now I just need to find another way of getting the name resolution to work.