There are usually many Windows services started that are not needed for a home user. Telling Windows not to load some of these can speed your machine up considerably. The list below describes some. It's recommended that you set them to "manual" and not "disabled". A manual setting will usually still allow the service to start if the system requires it.
When playing with the services, it's usually a good idea to change just one, then reboot, check the functionality of the machine (test it and play around etc) before changing anything else. Going ahead and changing the startup of 10 different services then finding out your machine isn't working properly is no fun to fix!
Remember that each PC is different and some situations will require these services and some will not! Use discretion when playing around with them and make sure you have backups, as (like playing with the registry) a wrong move can render your machine unusable! This is not a comprehensive list of Windows services either, as different setup options add different functionality. The suggestions below are aimed at home users who are not part of a domain or workgroup environment.
You might think that this is a prime candidate for turning off for a home user, however for some reason, disabling Event Log can cause Dial Up Networking to not function. So for dial up Internet users, especially, it's best to leave this one on Automatic.
The Protected Storage Service is a service which is related to Internet Explorer. Its best to leave this set to Automatic, as setting it to Manual can cause a delay at startup of 1 to 2 minutes. It also has the odd side effect of causing property pages in the Services tab not to appear.
Net Logon supports pass-through authentication of account logon events for computers in a domain. If you are a home user that does not need to log onto a domain, you can set this to manual. However if you do need to logon to a domain, you need to keep this on Automatic. Otherwise, it can cause you to wind up not being able to log on properly.
This feature notifies selected users and computers of administrative alerts. A home user can set this to Manual.
This maintains a list of computers on your network for things like My Network Places & such. A home user can set this to Manual.
Distributed Link Tracking Client
This sends notifications of files moving between NTFS volumes in a network domain. A home user can set this to Manual.
Distributed Transaction Coordinator
This coordinates transactions that are distributed across two or more databases, message queues, file systems, or other transaction-protected resource managers. A home user can set this to Manual.
If you have no intention of using the Modems Fax capabilities, you should set this to Manual.
This feature indexes contents of files on computers. A home user can set this to Manual.
Internet Connection Sharing
If you are sharing an Internet connection on a small home network, then set this to Automatic. If not, set this to Manual.
IPSEC Policy Agent
This manages IP security. A home user can set this to Manual.
Messenger sends and receives messages transmitted by administrators or by the Alerter service. A home user can set this to Manual.
NT LM Security Support Provider
This provides security to Remote Procedure Call programs that use transports other than named pipes. A home user can set this to Manual.
Performance Logs & Alerts
This configures performance logs and alerts. A home user can set this to Manual.
If you don't have a printer installed (network or local), you can set this to Manual. Remember to change it back to Automatic if you ever do install a printer.
This feature provides network signaling and local traffic control setup functionality for QoS-aware programs & control applets. A home user can set this to Manual.
Remote Registry Service
Allows remote registry manipulation. You should set this to Disable.
Routing & Remote Access
This offers routing services to businesses in local area and wide area network environments. A home user can set this to Manual.
This enables starting processes under alternate user IDs. A home user can set this to Manual.
Security Accounts Manager
This stores security information for local user accounts. Unless you have changed some security policies via the Local Security Policy editor, you can set this to Manual.
Smart Card and Smart Card Helper
A home user can set these to Manual.
TCP/IP NetBIOS Helper Service
This service enables NetBIOS name resolution. A home user can set this to Manual.
A home user can Disable it altogether.
A home user can usually set this to manual, as it's used for when you use a DNS server on your network (i.e., not the Internet or dial up connections). If you have name resolution problems afterwards, put this one back to Automatic.
This Provides RPC support and file, printer and name pipe sharing. You can set this to manual, unless you are running IIS or using offline files (or similar features), which is not that likely for a home desktop user.
This service provides network connections and communications. You should be able to set this to Manual unless you use Alerter or Messenger, in which case set this to Automatic. Otherwise. you should be able to safely set this to Manual instead.
WMDM PMSP Service
This service is apparently part of Media Player, however, setting it to Manual does not seem to have any ill effects. I suggest it's set to manual. If you have any problems with Media Player, set it back to Automatic.
Once you have a stopped unwanted services and you are happy that your machine is functioning correctly, you can check the Services applet in control panel again. Look for any services that you set to manual that have started by themselves -- this usually means that Windows has determined it needs that to start. Changing these services back to Automatic is a good idea.