Just noticed you have the Business Edition of Vista.
Looking at the
Vista comparison chart it doesn't look like the Business Edition supports
photos and entertainment
Windows Media Center
Easily make DVDs with Windows DVD Maker
Create high definition movies with Windows Movie Maker in High Definition
From this I would suspect it may be possible to install a third party DVD Player but you would also need to install a codec - I doubt the Business Edition has any built in after looking at the comparison chart.
I would have thought WinDVD would have installed a codec automatically but obviously not. You can check our
links to Free stuff for an alternative DVD Player. I know from past experience that
Power DVD (not free) installs a codec. Once a codec is installed then all other DVD capable players on your system will use that codec.
e.g. Windows Media Player