Results from Monte Carlo studies of the operation of a microstrip gas counter are presented. The Monte Carlo was tuned on data from test beam measurements using minimum ionising particles and DME/CO2 60/40 as a counter gas. We determined the position resolution of the detector for minimum ionising particles in different geometries and as a function of the incoming angle of the particle. It is made plausible that a position resolution of about 20 μm can be obtained by increasing the gas gap and/or reducing the anode pitch. The performance of a thin gap MSGC is also discussed.