Can Not Play DVD on my Computer

I just got my DVD Burner and have movie that was copyied for me but when I try and play it on my DVD I get a message saying I need some Plug-in for Windows Media Player and it cost. I'm running XP Home so what should I do to be able to play DVD's that have been copied? Is there free software I can get? If so where and whats its called? Thanks

 

Realplayer (free version) will play DVDs without a problem

Also, check out for following link for many more free software DVD players:
http://www.download.com/3120-20_4-0...nk=&gfiletype=&os=&li=49&dlsize=&ca=&x=36&y=8

 

You can even use power dvd or windvd. they all work fine, ask me if you want a url for the download...