If you have installed PHP in Windows using the PHP msi installer I am sure you have come across DLL hell.
Once PHP is installed, say you want to make it work with MySQL or CURL, then there are a tons of posts out there that ask you to place various DLLs in various locations. All these DLLs are just a google search away but if you blindly place them at the appropriate locations, PHP refuses to boot giving some reason. I went thorough this hell and this experience has made me wiser.
Say you have installed PHP version 5.2.8 using the msi installer and now want to make it work with CURL. You read a blog post asking you to download tons of DLLs and place them at various locations. Now the question is from where you should download them? Go to php website and download the zipped version instead of the msi installer. Unzip this and you should find all the DLLs you want. Choose the one you want and place them in their appropriate places.