Is Postgres comparable to MSSQL

Hello,
    I am a network/security guy not a dba.  A friend is a developer/dba type.  We
often debate whether open source software is viable for the enterprise or our
50 person company.  He doesn't know much about Linux or opensource yet is
very dogmatic.

    One argument he makes repeatedly is that there is no database that is
enterprise worthy for a cost even comparable to MSSQL.  He says that
Postegres is not even in the same class as MSSQL, DB2, Oracle.  He often
points to the db benchmarks which of course, pg is not involved in because
you have to pay be involved.

    I thought that pg was on par with these, that is to say that in all but the
most demanding applications, you would never see the difference between good
implementations of each one.

    Please let me know if I am wrong.  I would love to have some serious examples
to show that opensource is not a "toy" and can be used effectively in the
enterprise with all of the regular enterprise features.  I am sure everyone
is tired of comparison questions, but comparisons would be ok to.

    He probably still won't admit to it, but at least we will both know. :)
--
Andy Hester
Network Engineer
Galactic LTD