For Windows you path should be like this:
extension_dir = "c:\php\ext" (windows style)
rather than ../../ext (unix style)
Also, I often either put the path to PHP, the EXT folder and MYSQL stuff in the PATH environment variable of the Windows server, or alternatively you can simply copy the dll to C:\windows\system32.
I'd try the last one first, because it does not require a reboot.
