While I think of it, ssh -X 192.168.0.11 won't work without xauth loaded onto the N900.

To do this, become the root user (you really need to know what you're doing from here on) and install:

1) sudo gainroot
2) apt-get install libxmuu1
3) apt-get install xauth

Don't worry about all the posts everywhere talking about compiling and loading this and that package. xauth is just there now.