Vncserver2x motivated me to setup USB Networking, so I might as well post the steps I took. I have firmware 2.1.1, and Windows XP.
1.
Read the Networking setup tutorial
Go to the firmware 2.0. section and follow all the steps; before going to Control Panel's Network Connections, download
these drivers; when Windows asks you to set up the device, point it to the folder where you extracted them.
2.
Download vncserver2x
Extract the folder, but before putting it on your SD card, make one more file called vnc.gpe (in the vncserver2x folder). You must edit this file with a text editor that supports Unix line endings. I suggest
Notepad++ (there you just select Format > Convert to Unix format). Put the following in the file vnc.gpe
CODE
#!/bin/sh
./vncserver2x &
sync
cd /usr/gp2x/
exec /usr/gp2x/gp2xmenu
then save it (don't forget, Unix format!). Copy the whole vncserver2x folder somewhere on your SD card.
3.
Run vnc.gpe from your GP2X, the screen should go black for a second, then go back to displaying the GP2X menu.
4.
Get a VNC viewer, I got the free
RealVNC (standalone version)
5.
Run vncviewer.exe, type 10.1.0.2 in the server box, then hit OK. A window with the GP2X menu should appear on your computer monitor.