I set up a Windows server as a WAMP server (Windows, Apache, MySQL, and PHP) to run vBulletin. Everything worked fine, and the learning curve was pretty short.
Then I tried getting PHP to connect to a remote Microsoft SQL server. Sorry, no luck!
The apparent fix required an updated ntwdblib.dll. The one that came with the latest PHP5 bits (5.2.6) was apparently out of date (version 2000.2.8.0). A newer one, which I founded linked to from a UserScape support page, is version 2000.80.194.0. Shut down Apache, download the newer DLL (replacing the old DLL), and restart Apache. Viola! Hello, MSSQL server.