Because Windows XP has to be all things to all people it has many services running that take up system resources that you will never need. Below is a list of services that can be disabled on most machines:
Alerter
Clipbook
Computer Browser
Distributed Link Tracking Client
Fast User Switching
Help and Support - (If you use Windows Help and Support leave this enabled)
Human Interface Access Devices
Indexing Service
IPSEC Services
Messenger
Netmeeting Remote Desktop Sharing (disabled for extra security)
Portable Media Serial Number
Remote Desktop Help Session Manager (disabled for extra security)
Remote Procedure Call Locator
Remote Registry (disabled for extra security)
Remote Registry Service
Secondary Logon
Routing & Remote Access (disabled for extra security)
Server
SSDP Discovery Service - (Unplug n' Pray will disable this)
Telnet
TCP/IP NetBIOS Helper
Upload Manager
Universal Plug and Play Device Host
Windows Time
Wireless Zero Configuration (Do not disable if you use a wireless network)
Workstation
To disable these services:
Go to Start and then Run and type "services.msc"
Doubleclick on the service you want to change
Change the startup type to 'Disable"