Although Windows XP have remote desktop function, most people still like to use VNC to remote control their machine, however you may need to change the port to bypass the firewall of your office/school. Here's the way to change the port settings.

- If you want to set port > 5900:
1. Run WinVNC (App Mode)
2. Right click and select "Properties" on the VNC tray icon
3. Check "Accept Socket Connections" but DO NOT check "Auto"
4. Calculate display number: if you want to set to port 6900, then your display number will be: 6900 - 5900 = 1000
5. Enter 1000 in the display number field
6. Done

- If you want to set port < 5900 (e.g. port 2000), this reqire a few more steps:
1. Run WinVNC (App Mode)
2. Right click and select "Properties" on the VNC tray icon
3. Tick "Accept Socket Connections" but DO NOT click "Auto", enter "0" to the "Display Number" field.
4. Exit VNC server
5. Start -> Run -> regedit -> OK, Find "\HKEY_CURRENT_USER\Software\ORL\WinVNC3"
6. Find value of "PortNumber"
7. edit the value, change the DEC value of 5900 to the port number you want
8. restart VNC Server, Done!

When you connect to your machine by VNCViewer, type "your-ip:PortNumber" to connect (e.g. "192.168.10.51:2000")

And the web port is the value of PortNumber - 100, so if PortNumber = 5900, http port = 5800, then you can access your desktop in a browser by "http://your-ip:PortNumber", (e.g. "http://192.168.10.51:1900")

Hope this can help