After spending a couple of days trying to optimize various aspects of my WinXP installation, I managed to reduce the list of services running on my PC to the following:

Application Layer Gateway Service
Atheros Configuration Service
COM+ Event System
DHCP Client
Event Log
Network Connections
Network Location Awareness (NLA)
Plug and Play
Print Spooler
Remote Procedure Call (RPC)
Security Center
Task Scheduler
Windows Audio
Windows Firewall/Internet Connection Sharing (ICS)
Windows Management Instrumentation
Wireless Zero Configuration

My PC connects to the home router via a TrendNet wireless USB key, which is the reason I have those two services - Atheros and Zero Config - running.

I'm wondering if there are still services which I might as well disable without affecting the normal operation my PC, or if I disabled too much.
I'm especially curious about "COM+ Event System", I tried to make sense of its description in the services applet, but I find it very obscure.

Im only guessing here, but I would say that the COM+ Event System handles the event viewer - which logs every time something happens (good or bad ) Go Start > Run > and type in eventvwr, then you will see what the event viewer does.

My guess is that the COM+ service, keeps the logs updated!
-jimmy

if you don't use it, you can disable the task scheduler service too.
for more info on COM+:
http://www.blackviper.com/WinXP/servicecfg.htm
http://www.theeldergeek.com/services_guide.htm

Of course turning off services will boost performance. It tags less memory and processor processing.

xboxrulz

To add up, if you really want to boost your computer's performance, try disabling the Visual Effects of Windows XP and observe it.

This is quite possibly one of the best windows memory-usage tuning guides out there...I've been using it for years when I set up new systems.