load XP service pack 3 to his computer, or should he wait a little longer?

he should have the good sense to use linux instead.

Thanks for that helpful reply , artificer

I think it is safe - though I had I have had great trouble this week trying to download Windows Service Pack SP3 - it just would not start downloading and kept giving an error code that third party software must be interfering.  I have never had a problem like this before. I messed for ages switching off AV and Firewall etc and went through all the Microsoft "self help" solutions on their web site, all to no avail.

By Friday afternoon I was sick of it and filled in a customer service form to ask for help (free service when related to Windows updates).  I got a full reply during the night ready for me when I switched on this morning.  The person concerned had clearly read all my details and referred to them in what was otherwise obviously a fairly standard reply to a routine (to them) problem.  The email gave me a link to an alternative download site to allow me to download to my desktop and then install in safe mode (details of how to do this were very full and clear).  A follow on action list was included for what to do if this didn't work.  It did work though and the job was completed in about an hour.

It's not often that Microsoft get praised but I certainly found them very helpful, very timely and very clear and reassuring in their response.

Downloaded SP3 this week and have had no problems.

Beware !  It is not a problem for PCs with Intel processors but many AMD processors will fail.  Intel uses intelppm.sys to manage power, whereas AMD uses amdk8.sys to do the same task.  HP recognise that Service Pack 3 will enable intelppm.sys to run on their AMD processor systems redundantly, which can cause everything to crash.  If you have an AMD processor, then firstly ensure that you have created a RESTORE point to which you can return BEFORE downloading Service Pack 3.  If the download works satisfactorilly with an AMD processor, then no worry - sometimes it does, sometimes it creates huge registry problems.  Microsoft seem to be aware of the problem but HP are reporting a very large number of failures. 
If it does not work, then you will have to go into safe mode and restore the system to Service Pack 2, disable intellppm.sys and try again.  So the advice is that if you have an AMD processor, then you should consider leaving Service Pack 2 in place for the time being, until the dust has settled.  Service Pack 3 is only a consolidating update; it adds little, if any, value except providing a new benchmark.