Quick poll: Favorite VNC Server for Windows?

Hi,

Just wondering if anyone has any recommendations for a Windows VNC Server. We've been using UltraVNC for years and it's still fine, but we've been having issues with the later versions with time outs and crashes. Does anyone have a suggestion on a stable, modern, open source VNC Server package? Preferably one that has seen serious field usage and has proven robust on many different quality network links.

Thanks!