This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
From the services window, right click on the service and choose 'Properties' from the menu. Then, click on the "Log On" tab. By default, it runs under the Local System Account. You will see a radio button that allows you to change the account. You'll have to enter the accountname and password. Then restart the service.