It is now several years since scientists in Poland can use the resources of the distributed computing infrastructure - PLGrid. It is a flexible, large-scale e-infrastructure, which offers a homogeneous, easy to use access to organizationally distributed, heterogeneous hardware and software resources. It is built in accordance with good organizational and engineering practices, taking advantage of international experience in this field. Since the scientists need assistance and close collaboration with service providers, the e-infrastructure is relied on users' requirements and needs coming from different scientific disciplines, being equipped with specific environments, solutions and services, suitable for various disciplines. All these tools help to lowering the barriers that hinder researchers to use the infrastructure.