which Xeon processors don't have the context switching problem

I recall a reference on the list indicating that newer Xeon processors
don't suffer from the context switching problem reported last year.

In searching the archives, I can't find any specific info indentifying
which Xeon processors don't have this problem.

Anyone point me to a reference?

Is this in any way related to the version of Postgresql one is running?
  We're headed for 8, but have a bit of work before we can get there.
We are currently on 7.4.16.

Thanks for any info.
--
Until later, Geoffrey

Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety.
  - Benjamin Franklin