DDOL is the Drug Design Optimization Lab. It was created to find drugs to fight Anthrax, Smallpox, Ebloa, Botulism, and Plague. They can do a better job explaining it than I can so
read here to find out more.
It is a java client and I'm not sure about running it as a service. There have been problems with getting a bad packet and it stopping work but a simple restart of the computer or client can fix that and it doesn't happen much more than problems with other DC clients. It is simple to install and the client and tip on how to run it can be found
here.
Others I'm sure can tell you more than I can but I think I've covered the basics.