In Windows 7, 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.
BlackViper.com's list of Windows 7 services shows the default settings. I have tested safely disabling the following services - ActiveX Installer, Adaptive Brightness, Application Experience, Application Identity, Application Layer Gateway Service, Bitlocker Drive Encryption Service, Block Level Backup Engine Service, Certificate Propagation, Computer Browser, Distributed Link Tracking Client, Encrypting File System (EFS), HomeGroup Listener, HomeGroup Provider, Internet Connection Sharing (ICS), IP Helper, IPsec Policy Agent, Microsoft iSCSI Initiator Service, Netlogon, Network Access Protection Agent, Parental Controls, Peer Name Resolution Protocol, Peer Networking Grouping, Peer Networking Identity Manager, Portable Device Enumerator Service, Remote Access Auto Connection Manager, Remote Desktop Configuration, Remote Desktop Services, Remote Procedure Call (RPC) Locator, Remote Registry, Routing and Remote Access, Smart Card, Smart Card Removal Policy, SNMP Trap, SSDP Discovery, Tablet PC Input Service, TCP/IP NetBIOS Helper, UPnP Device Host, WebClient, Windows Biometric Service, Windows Image Acquisition (WIA), Windows Remote Management (WS-Management), Windows Time, WinHTTP Web Proxy Auto-Discovery Service.Since I am using a third party firewall, I can also disable Windows Firewall.