Software

If you install VNC server software on one computer, you can view & control the screen of that computer from another computer (client) which has a network connection to the VNC server computer.

So, that means that we can install the VNC server software on a Windows computer and control or observer that computer from a Mac, using the VNC client software. Or visa versa.

Very handy for carrying out remote maintenance, demos, supervision of remote students, or simply grabbing cross-platform screen shots for tutorial papers, etc.

Note: Screen Sharing is built-in to Mac OS X 10.5, so if you are using this OS on your computers you probably won't need any of the software below.

Install on the computer being shared...
Macintosh

Apple Remote Desktop
OSX VNC (Free)
OS9 VNC (Free)
Share My Desktop (Free)
Timbuktu Pro

Windows

Real VNC (Free)
TightVNC (Free)
Timbuktu Pro
MasterEye - Vision6

Install on the remote viewing computer...
Macintosh

Screen Sharing (part of Mac OS X).
Chicken of the VNC (Free)
JollysFastVNC (Free)
VNCViewer (Free)
VNC Dimension (Free)
Timbuktu Pro

Windows

Real VNC (Free)
TightVNC (Free)
Timbuktu Pro

• The most common port number for VNC is 5900.
  
  
• If you are using Apple Remote Desktop (ARD) on your Macs, you can install the VNC server software on a Windows machine and control a Win desktop from within ARD.
  
  
• If you have ARD client enabled on your Macs, you can control your Macs from VNC on a Windows computer. Just enabled the VNC option in ARD on your Macs.

NoMachine NX

Remote desktop management using a faster protocol to VNC.

CoRD

Mac OS X remote desktop client for Microsoft Windows computers using the RDP protocol. Free. (Alternative to MS RDC Client.)