I have struggled with this until im fed up with it.
Here is my experience on the subject maybe it will help someone fix the issue.
ppc conects to net fine but when tried messenger it said not compatible.
uploaded the patch (yes it was correct version) did not work
until you do a soft boot ( you must do this, the patch even tells you too)
i now get the messege that the service is temp. unavailable
i contacted msn messenger for ppc, they had me hardboot and start over it did not work so they refered me to
support@microsoft.com
in their reply i was told that it seemed to be a problem for my hardware vendor (that quote should sound familar to any tech)
i havnt talked to dell yet as I needed a break from the task(will do this week)
Kudos to the users of this site for it has been more helpfull than all other sources