Identify third-party servicesOn a properly running system, most Windows services run predictably. Third-party services are much more likely to run amok and use too much memory, CPU, or disk I/). To see a concise list of third-party services, open the System Configuration utility (Msconfig.exe), click the Services tab, and select the checkbox circled at the bottom of this dialog box. As a diagnostic tool, you can temporarily disable a service by clearing its checkbox here and then restarting.
For a detailed discussion of when and how to manage services, see Fixing Windows Vista, Part 4: Get smart about services