Windows 7 - Ripped movies not displaying properly on Sony Bravia XBR-55

My apologies in advance if I'm asking a question that's already been asked or if I'm not providing all the appropriate details...I'm new to this conference.

I'm attempting to set up a Home Media System for my muli-handicapped son who's passion in life is movies. This approach should greatly simplify the end-to-end process for him. OK, now for the problem and where I can use your help.

Here's my attempted set-up

• I'm ripping his DVD movies to MP4 using WinX-DVD Premium Ripper
• Storing the movies on an external 2TB harddrive connected to my DELL desktop running Windows7 Ultimate, 64-bit
• Using Windows Media Centre / Media Browser to stream & display the movies
• Running the movies thru a new Xbox-360 (using MC extender), connected to
• Xbox is connected to Sony Bravia XBR-55 via HDMI (HDMI 2)

Here's the problem I'm encountering

• I'm ripping all the DVD's using the exact same format
• Some of the movies are displaying "full screen" while some of them are only displayed on 2/3's of the screen - right in the middle
  Note: These are Full Screen vs. Widescreen movies.
• The movies I'm experiencing this problem with work fine if
  • I run them from the DVD player (i.e. Google TV - these are NOT Blu-ray DVDs)
  • I stream them from the computer, via WMP straight to the Sony TV - this approach is supported, but with an antiquated interface...ugh!

Any ideas on what I can do to rectify this problem? Also, any ideas you have to further simplify this overall process for my handicapped son would be welcome and greatly appreciated. Thanks in advance for your help.

Sorry for my naive questions, but I'm just learning the Digital Media world

Here's where my confusiong lies...
1. If I play the movie (i.e. Cars, Head of State, etc.) on my DVD player, it displays in Full Screen.
2. If I rip these DVD movie to MP4 (using WinXdvd Premium Ripper) the only way I can see them in Full Screen is if I manually modify the "Picture Display" on my Sony Bravia from "Full" to "Wide".

Not all DVDs behave like this and I have no idea why this is happening or what I can do to resolve it with the manual intervention.

Hope this is making sense Thanks for any advice you guru's provide.