I tried several media players with both XP and Win7.
I liked Media Player Classic, but it would not play some files.
Most recently, I have found VideoLAN (VLC) to be the better one currently. It plays most video formats, including the weird WindowsTV (WTV) format.
It is also available for Windows, Linux and numerous other OS.
I’ve had downloads that won’t play on anything BUT VLC, But I still like MPCSTAR. You just have to pay attention to what you click on as you install it.