At the time of writing version 6.2 was the current stable version of the Folding@home client. Just looking at the project's download page shows multiple clients that are currently in use, this is mainly due to the fact that they support a number of operating systems and different hardware platforms.
The main types of client are:
"The Console client runs in the background and is launched from a terminal window (command line i.e. DOS window), to which they output text messages about the simulation's progress." (Folding@home, 2000-2010) these clients can be a little difficult to initially get set up, but once running can be easily be forgotten about and left to their own devices.
"The graphical clients (former GUI or current System Tray) run in the background and has a graphics window interface that allows you to see the protein being simulated." (Folding@home, 2000-2010) these clients are not used as much as they used to be due to the GUI included uses a lot of the systems resources that could be better used for the work calculations, they are usually bundled in an installer so that they can be easily installed.
"Clients [released] early for donors to beta test." (Folding@home, 2000-2010) these clients can be quite unstable due to the fact that they have not been fully tested yet and therefore may contain bugs.
"These clients use more system resources, but are also much more productive." (Folding@home, 2000-2010) these clients usually run against top-end hardware and specialised hardware such as GPUs and the Sony PlayStation 3 games console, I will not be working and testing against these clients yet as I do not believe it will be possible within the time scale of the project. However, they could be supported at a later date to be included in future work.