Yes bpark X11 over ssh workes fine if you have a X-server (like on linux or sun) but if you must work on a Winblowze computer you must have a xserver to be able to see X stuff from unix/linux. Thats when VNC is good. you can have a tiny client on the winbloze box and work with linux X programs.

If you are using reflection X or something in winblowze you can use X11 over SSH. Then reflection X is acting Xserver.