1. Download MCE Tweak
2. Download DVD Shrink (Use this to rip and compress the DVD. Save the output in a folder inside of your "My Videos" folder. Name the folder you create to reflect the name of the DVD. Download a picture of the DVD cover and save it in the folder along with the DVD file and name the picture "folder.jpg".
3. Install MCE Tweak. when you run Media Center, there will be a new addition to the menu list. It's called My DVDs. When you select it, you will see an image of the DVD you just ripped. When you click on it again, it will give you the option to "Watch". Select Watch and the DVD you just ripped will start playing in MCE.

I hope that was clear enough to follow. Mess around with it and you'll get it.

Also, if you have a lot of DVDs, you can get an External Harddrive Array. It's basically a box that holds multiplt harddrives and sets them up as 1 BIG drive. Move the target of My Documents to this new drive, and save all of your DVDs on the new drive in the My Video folder. You can get these arrays in 2 or 4 disks. The NspireGear NSP-E350W4U holds 4 HDDs with a total capacity of 3TB max. It's about $150.00 and connects via USB.

If you want to be able to access the movies from any PC on the network, get yourself a NAS. It's basically a HDD Array that attaches to your router.

Best of luck.