Computing resources of both hardware and software tends to be located at a certain place, as most professional software supplied by a computing Grid demands powerful computing hardware. The computing Grid in this paper provides work processing with legacy professional software, without any modification or adaptation of the software. A simple model of computing Grid composed of computing sites is designed with commodity components. The simplified computing Grid model consolidates computing sites in manageable, transparent way. A client connects to the computing Grid with a Web browser. The access to the user data is allowed only after user authentication. The model is under implementation in the form of Web service.