Or you might need the software to run the DVD. That was a problem I first encountered when I set up a dual platform in a computer a couple of machines back.

I think Windows Media Player will play DVDs now. My Nero has something for playing DVDs (though it doesn't look like much). I prefer the program WinDVD which has been around for a few years and can be purchased for about $10 as OEM through places like eBay ($5 for the program and they gouge $5 for shipping a single CD, but still, it's low compared to paying full price for it and the old program is in some ways more reliable and last I checked still got better reviews than the newer version).

SRS