DVD Data recovery

I am unable to access files I have on a DVD-R disc throught my DVD Rom drive. The disk contains just ordinary files which I wrote onto it with another computer with Vista however I am unable to access them through my own PC (running Windows 2000). The only software I have found so far that can access the files is Isobuster thought only the full version will extract files from the disk, at 25 Euros it seems a bit excessive for a piece of software I will only use the once but as I need to have the files I am on the verge of buying it. Anyone know of any free alternatives software that can copy files from a DVD-R?