PostgreSQL vs. Oracle vs. Microsoft

I'm looking for recent performance statistics on PostgreSQL vs. Oracle
vs. Microsoft SQL Server. Recently someone has been trying to convince my
client to switch from SyBASE to Microsoft SQL Server (they originally wanted
to go with Oracle but have since fallen in love with Microsoft). All this
time I've been recommending PostgreSQL for cost and stability (my own testing
has shown it to be better at handling abnormal shutdowns and using fewer
system resources) in addition to true cross-platform compatibility.

If I can show my client some statistics that PostgreSQL outperforms
these (I'm more concerned about it beating Oracle because I know that
Microsoft's stuff is always slower, but I need the information anyway to
protect my client from falling victim to a 'sales job'), then PostgreSQL will
be the solution of choice as the client has always believed that they need a
high-performance solution.

I've already convinced them on the usual price, cross-platform
compatibility, open source, long history, etc. points, and I've been assured
that if the performance is the same or better than Oracle's and Microsoft's
solutions that PostgreSQL is what they'll choose.

Thanks in advance.