I love PHP big time (but I certainly am no expert) so don't get me wrong. But I've done a lot of research Almost all of the PHP developers are using the non-threadsafe version because the threadsafe one is unstable. My understanding is they didn't even ship the latest version of PHP with an isapi module because of the problems with it. But I don't think this is a really big deal for most people out there other than FaceBook and several hundred other really really large scale sites. Same thing with a 64-bit PHP - it just doesn't matter, so why do it? And I don't think there is even a serious effort to make a 64-bit PHP version. (VFP is always run compiled so you don't have to make an additional effort to do that.)
PHP is GREAT because it is so easy and there are literally tons of 3rd party apps for it out there . My fav is WordPress..

>>PHP has a windows thread safe and non-thread safe version for windows. Also, the Facebook people have built a complier for PHP. Last fall I went to a ZEND PHP conference and watched the CIO of the NYSE present a case study about how he was hired to hurry up a two year project that was not getting completed. A month latter he dumped the project and started over with PHP and had the project deployed in 8 months. I also watched a case study from GE that was impressive. What surprised me the most was how many very large companies use PHP. Dismissing PHP is a big mistake. Its problem is it does not get the press because it is open source.