The best place I have found on the net to play is www.truemoneygames.com. The reason it is the best is that if the game is interrupted for any reason, TMG using a program called Snowie, the best backgammon software out there to determine each players equity in the position, and divide the monies accordingly.
Also the actual playing software is the best out there, easiest to use.
Look me up if your are there, I am "pokherplyr" there also