Not a bad guide guide!

A few comments, some realting only to XP Pro so if the service isn't there you know why:

The easiest way to access the services console is by going to run and entering "services.msc" and hitting enter. This is the same for all languages.

The DNS client is almost never required. It actually caches DNS lookups and then refers to them for future queries instead of referring to the remote server. Personally I disable it. If you go to run, enter "cmd" and then in the terminal windows enter "ipconfig /displaydns" you will see the contents of the DNS Resolver Cache. To me this is just a gimmick. Yes it may be quicker than having to perform a real DNS lookup but the difference negligable.

The computer browser service is a core part of the "My Network Places" functionality. If you use "My Network Places", then do not disable the Computer Browser service. The computer browser service also won't function correctly if the Windows ICS/ICW service is disabled (the Windows NAT router). I don't know why this is, it appears to be a bug, but if you disable the ICS/ICW service, Computer Browser won't work properly. This bug was introduced with SP2. Note: Enabling the ICS/ICW service doesn't mean that the NAT and firewall are actually runnning and IP routing, the service is running and that's all.

Event log is quite important. I often go through the event logs to trace faults. You can see those services or drivers that are failing on start up and find the cause of crashes and other issues. Once a system is running optimally though it probably should be turned off.

Quite a few services have been omitted from that are also quite important.

The DHCP Client is one such service. You'll either need it or you won't. If you're connecting via an hardware NAT router, then you won't need it as you assign a static IP address and not use DHCP at all. This speeds up connection times and is one less service running.

If you don't have a printer, you won't need the Print Spooler.

Another 'gem' is the Remote Access Auto Connection Manager. This service is the junk that allows your internet connection to connect automatically when requested by a program or other pc on the network. If you don't have a network and don't want annoying programs, possibly malware, to be able to connect to the net on demand, then it should be disabled.

The Server service, should also not be running if you're not sharing anything. This can be a security risk.

Task Scheduler. If you're not scheduling back ups or other tasks it can be disabled. There is some piece of M$ crapware that does depend on this, but I can't remember it offhand.

Fast User Switching is also junk. First go to the control panel -> users -> change the way users log on -> use the welcome screen OFF -> use fast user switching OFF. Then exit and go back to the services manager. Disable and stop the Fast User Switching service.

IPSEC Services is also likely to be running. In its out of the box form XP doesn't make use of any IP Security Policy. So it's best to disable this.

When I think of some more I'll post some more.