Xine is the best DVD player I have ever used, but I'm not sure if it works for Windows. It takes some work to get running, but is fast and fully-featured (and stable as a rock

).
Beyond that, try doing a google for MikSoft DVD player. Pretty sure it doesn't have spyware (may want to run a check just to make sure), but it is very simplistic and a little sluggish.
I use MSIDVD in Windows, which is an MSI'ified version of WinDVD. Works very well.