Among them, RealVNC is by far the most mature, but only in its paid incarnation. RealVNC, TightVNC, and UltraVNC all support Windows hosts and clients and provide browser-based access via Java, but none of the free releases provide remote printing. Performance is on par with the other remote access tools listed here, and the Java version is no exception. VNC is not as firewall friendly as Gbridge, LogMeIn, and TeamViewer, requiring a specific port to be forwarded to each target host.
Installation of VNC is quick and easy on Windows hosts up to Windows XP and Windows Server 2003, including 32- and 64-bit versions. TightVNC is available in a beta version for Vista and Windows 7, while support for these platforms comes via the paid version of RealVNC ($30). After you've installed the host and client software, your network admin will have to open a port in the firewall and point it at the VNC host before a remote user can connect. As with Remote Desktop, a different port must be used for each additional host.
Remote clients will have to connect to either a fully qualified URL (such as vnc.mydomain.com) or the external IP address of the firewall. It's not as elegant as logging into a Website and clicking your host PC out of a list of available devices, as you do with LogMeIn, but it works. It just requires a little more coordination between IT and the remote users.
None of the free versions of VNC support remote printing, but the paid version of RealVNC does. TightVNC and UltraVNC both allow file transfers between host and remote client as part of the free package, while this too is a paid feature in RealVNC.
Overall, the three major VNC releases work well with Windows hosts and provide an intuitive platform for remote control. Unfortunately, the lack of printing support keeps TightVNC and UltraVNC from being a first choice for anything but remote control needs. The $30 license for RealVNC is still a good deal, but most Windows users would be served just as well by Remote Desktop.