Benchmarking PGSQL against Microsoft SQL 7.0?

Please forgive my newbieness but I am extremely new to both Postgresql AND
Linux. I've been a consultant for 6 years working mostly on Microsoft
platforms (NT, MSSQL). I have developed many data-driven websites using
WinNT/IIS/ASP/MSSQL. Now, getting sick of MS and being enamored with the
whole Open Source movement, I wish to learn (and develop a project or two)
on Linux/Apache/PHP/PGSQL.

I was wondering if anyone has done any benchmarking (even roughly),
comparing PGSQL to Microsoft SQL Server 7.0 or even the older MSSQL 6.5.
Specifically I just want the reassurance that the two products are in the
same ballpark as far as performance goes. Has anyone done this recently?

Thank you,
Bryan