Accessing DLL from PHP

Hi list I do not have much programming experience outside some PHP stuff so please excuse a stupid question: I have a DLL provided to me by a third-party with a small bit of documentation regarding its structure and methods. The DLL caculates event costs based on parameters passed to it. I would like to access this DLL using PHP if possible. I have RTFM, and I am still busy STFW and STFA, but the little bit that I have found has lead me towards trying to understand COM (eek!). Before I go down that particular garden path, I would like to know if there is any chance of success with PHP, or should I look at non-PHP alternatives to access the DLL (e.g. C?) Regards Rory