I wouldn't use PostgreSQL on a Windows system, unless there was a real need for something specific, such as PostgreSQL's added datatypes and functionality, or if you need it as a development workstation to develop apps to be run on a Unix server.
PostgreSQL was written for Unix first, and can only be run on Windows through the use of a Unix-emulation library, such as Cygwin. It definitely will not perform as fast on Windows as on Unix. MSSQL is a better choice if performance is an issue.
However, PostgreSQL is free, and MSSQL is not.
One possibility: get a secondary cheap computer to run Linux or FreeBSD, and make it your PostgreSQL server. You can connect to it over the network using PostgreSQL's ODBC library, so your windows machine can still be your main PHP server. This will give you an incredibly stable, fast database for a very low price. -------------------------------------------
"Calculus is just the meaningless manipulation of higher symbols"
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