Has McAfee successfully installed, been updated and run? I know this sounds silly but there are some, out there, who have never Updated or Run their Anti Virus?
You make no mention of a Fire Wall.
Has he cleared out all the usual Temporary files and Recycle Bin, Defragmented and then run XP's full Error Checking on his HDD?
None of these is likely to make any difference most of his problems but will start him on the road to a cleaned future.
Remember to tell him to set a Restore Point before making any big alterations. I have been told that it is a good idea, when you know that everything is running smoothly, to clear the Restore Points by turning them "OFF" and rebooting. Remember to turn them on again.