The lite version is free and does not need to install any third party server components (tightvnc) on XP/2k3.
To access the PC, local or remote, over the cable from iphone you need to add extra reverse tunnel in Tunnelier configuration, see S2C section.
For example, if you'd like to connect to the Desktop of some r.no-ip.org machine add the following entry in the list
Then for connection over tunnel in Mocha RDP you need to add entry to 127.0.0.1 thru port 3389 and voila, you will see the remote desktop of r.no-ip.org on the iphone screen.Code:List. Int | List. Port| Dest.Host | Dest. Port 0.0.0.0 | 3389 | r.no-ip.org | 3389
If you still prefer to use vnc just change the destination host and port which vnc uses (5900) in reverse tunnel entry. Don't forget that on iphone you should then connect to 127.0.0.1:5900