Best environment for PHP on Windows

We have a website currently running ASP/IIS/Win2k. It has some problems that get it locked up on a semi regular basis, requiring a reboot or killing of dllhost.exe. I've started porting some of the code to PHP to see if this is a viable alternative. So far, I've been running it on IIS/Win2k as an ISAPI filter. I've found the performance to be subpar running against the same database backend server (MSSQL) as the ASP code. I downloaded a copy of apache, although I've not installed or tested it. I'll grant that the ASP code and the PHP code are running on separate machines, although they have the same hardware configuration (the PHP machine even has a lighter load because I am the only one using it - there are 20-30 people on the ASP machine all day long). What is the optimal configuration for running PHP under Windows? IIS/ISAPI? Apache/CGI? Apache/mod_php? If I'm going to give this a fair run, I'd like to do it under the optimal conditions for PHP. There does not seem to be sufficient support for accessing MSSQL under linux. I've tried freetds, but it doesn't have full support - running stored procedures with mssql_init() mssql_bind() mssql_execute() won't work. We can't get away from MSSQL - our accounting system runs on it, and that's not going to change.