quality of service levels

[Gary Reid]

has anyone sucessfully put limits on a VS? cpu, memory, http connections,
mysql connections etc etc - so as to give a quality of service guarantee -
we could set some in httpd.conf but as VS admin has access to this it's not
such a good idea

Also how has anyone limited the actual number of virtual domains a VS can
add to the webserver? Additions to name servers are covered but customers
could use public dns etc

Gary