for a 19" display:
vncserver :2 -geometry 1200x900 -depth 16
in vncviewer, connect to
you might edit the $HOME/.vnc/xstartup
uncomment the two lines up top to get a nice gnome / kde desktop in your vncviewer, instead of the twm. Comment out the twm statement at the bottom.
Also, either turn off your firewall, or google what ports VNC uses, and open those ports.