In Vista, click start and type services and press Enter. Avoid the temptation to access your services via Msconfig, aka the System Configuration utility. The reason is because with msconfig and Hardware Profiles, you can disable services that may be vital to boot your system. With the management console (services.msc) you cannot. Also, msconfig, while unchecking the box, is disabling the service. But, you can use msconfig to stop the following services from startup - igfxtray & igfxpers.
BlackViper.com's list of Vista services shows the default settings. I have tested safely disabling the following services - Application Experience, Certificate Propagation, Distributed Link Tracking Client, Net Logon, Portable Device Enumerator Service, Remote Registry, Smart Card, Smart Card Removal Policy, SNMP Trap, Tablet PC Input Service, UPnP Device Host, WebClient, Windows Remote Management (WS-Management), Windows Time, WinHTTP Web Proxy AutoDiscovery Service.Since I am using a third party firewall, I can also disable Windows Firewall.