We present a detailed study of the transport properties of a superconducting Pb/Cu microdot with a 2x2 antidot cluster. The superconducting-normal (SM) phase boundary, critical currents, and current-voltage characteristics of this structure have been measured. The S/N phase boundary as a function of field B [T-c(B)] reveals an oscillatory structure caused by the limited number of possible vortex configurations that can be realized in these small clusters of pinning centers (antidots). We have analyzed the stability of these configurations and discussed the possible dissipation mechanisms using the critical current [J(c)(B)] and voltage-current [V(I)] characteristics data. A comparison of the experimental data of T-c(B) and J(c)(B) with calculations in the London limit of the Ginzburg-Landau theory confirms that vortices can indeed be pinned by the antidots forming a cluster and that the ground-state configurations of the vortices are noticeably modified by sending current through the structure. The possibility of generating phase slips as well as motion of the vortices in the 2x2 antidot cluster will also be discussed.