By default, in Windows Server 2003 Enterprise Edition sound disabled and in Windows Server 2003 standard Edition sound enabled by default. If your system sound is not working in Standard edition then check the drivers, etc. Once again, sound being disabled is not a problem for Standard users.
Step by Step
Click on Start, then Programs, and then click on Services from Administrative tools
Scroll down to service name list and find Windows Audio, and double click on windows audio, then set start-up to automatic, click on Apply, click on OK, and than click on Start