PostgreSQL vs. Microsoft SQL server

Anybody know of any recent comparisons made between the two?

I'm in the process of buying a new telephony related software suite,
and I'm getting mixed advice. Some say that MSSQL is _much_
better/faster than PostgreSQL, and others say the opposite.

The vendor is more or less indifferent, with a small plus to the
Microsoft solution because, well, they are a Microsoft shop. The
sales-people all bang on about MSSQL being the superior choice, and
PostgreSQL being a "toy compared to the Microsoft RDBMS". The tech
people though are divided into three groups: One group says the two
systems are more or less equal, another group who says the Microsoft
database is superior and finally a group who speaks highly of
PostgreSQL.

I've not been able to convince them to send me some actual benchmark
numbers, which actually should turn on quite a few alarms, come to
think about it.  :o)

Maybe you guys are aware of some recent generic tests/comparisons
between the two systems?

Regards,
Thomas