Well off hand, Indexing service, Error Reporting, Fast User Switching (unless you share PC with other users) can be disabled. Help and Support put to manual. I hardly use it. Actually I've removed it from my XP install with nLite.
Unless you are on a laptop, disable the Smart card service. You could maybe disable Secondary Logon. Unless you use the XP firewall or your PC is used to share the Internet to others, disable the XP firewall/ICS service. Perhaps park the Printer Spooler service into manual. I don't print much and by having the service in manual, XP just runs that for me when I do print.
I've never used the System Restore service. Some OcUKers will say that they see it as a threat. If you get infected with a virus, it might bed down nice and snug in the System Restore files so when you restore the files to put your PC back to how it was before the virus, lo and behold the virus is back again.
Do you have a broadband connection? If you do and you don't "dial-up" to anything such as a modem or a phone then you should be safe disabling the Telephony service. Computer Browser sounds important, my research tells me its for a network system. So unless you have a network disable this.
Windows Defender service can be disabled if you've gotten rid of that.
Do you have an MP3 player? If not might as well disable the Portable Media Serial Number service.
I personally disable the Security Center. I am quite capable of keeping my AV and FW up-to-date, they do it automatically for me.
You might like the help that it gives you though so your choice on that.
And lastly, any wireless cards in your PC? If not say hasta la vista to the Wireless Zero Configuration service.
These are just suggestions I'm making, comparing what you have running to what I've set them to. You might need some of the above for various reasons but I hope I've mentioned a decent number that you can rid of.