If the computer you are trying to connect to is a windows XP pro (not sure about home version) why not use the buildin RDP (Remote Desktop Protocol)? AFAIK it has better authentication and encryption as opposed to VNC. If that's not secure enough you can use SSH to tunnel RDP (just like with VNC).

You can find out more about Remote Desktop by right clicking on My Computer and choose properties. On the tab Remote you'll find the option to enable RDP and a pointer to a help file with some basic info.