I used to use Fantasy grounds, but Now I use a free Online Program called Maptools found at
www.rptools.net it's a Free and VERY useful program. it doesn't have a option for character sheets, But it does have 100 hotkey options for setting up Dice macros or anything else. Chat window works well and the Map Tool with it's fog of war ability is very Nice.
You can use the 1.2 version or the !.3 beta version.
The beta version has Video tutorials.
The program can be set up with line of site topography that Blocks the view of the PCs based on their position on the map and Light source.
been using Map tools for almost a year now.
Along with it I use a Ventrilo Voice chat server, makes communication during game easier. the chat window is msotly used for dice rolls and declaration of character actions.
Anyone Interested in using ventrilo for their Online game can contact me, My server has a capacity of 30 and most of the week it is hardly used. I can set up a Passworded private chat room for anyone interested. Donations are not required but not turned down either. :-P
I have my own groups that play using the Ventrilo server mabey 3 to 4 times a month plus 3 other groups that currently use the server on various days.
Don't be shy just contact me and I can set it up for ya.