: In this paper a comparison is provided between the membrane computing systems and the graphical interfaces of operating systems. A membrane computing system is a computing model using massive parallelism inspired by the functioning of living cells. The graphical schemes of these computing devices look like the windows of a graphical operating system representing programs running parallel on the computer. Both similarities and differences of membrane-systems and graphical operating systems are detailed as well as some possible simulation methods. Key Words: Membrane Computing, Operating Systems, Graphical Interfaces, Graphical Operating Systems, Parallel Computing