Hi guys. I owe you all an apology for being so obtuse in my original question. I was in a hurry and I did a poor job of asking my question.
I will go through your responses and will check out the link(s) provided, but first; a bit more:
This laptop, an Asus G73, has a big 17" screen and decent audio even through the speakers. It has Windows Media Center that came with Windows 7 from Asus. As I prepare to upgrade to Windows 8, I'm going through my mental checklist to try my best to not loose too much functionality, and it just came to mind that Windows 8 could remove my ability to play DVD and Blueray movies. I don't know for certain if the Windows 8 upgrade will end up disabling/deinstalling Media Center; I'm just trying to be prepared in case it does.
Background:
I use this laptop mostly as a mobile DAW when I'm travelling, and as an emergency diagnostics/download machine in case something happens to my desktop system at home.
If Windows 8 does end up disabling or deinstalling Media Center, then I'll want to at least be able to play movies on this laptop. Again, it's mostly only for when I am travelling and might want to watch a movie. I think that's all I really need at this time; the ability to play any DVD movie in the US zone/region, and because I haven't even had need to use Media Center in 2.5 years, I'd rather not spend a significant sum just to have the ability to watch movies. No need for ripping, copying, or backing up DVD movies; just watching is all I think I need.
EDIT: I have checked out the links for VLC and XBMC, and I think either one of them could very well serve my needs. I'm downloading XBMC at the moment to check it out this weekend.