Video Stuttering When LiveTV is Out of Focus

Not necesarily. If you feel comfortable with trying to troubleshoot your issue, you can review the many tutorials here (see horizontal menu on top of page), or use the forum search features. I will be glad to help, but it will certainly be much easier to help if I do have those specs.

Here is what I recommend for forum members to easily gather your system specs and post them here:

1 From the start menu, in the lower text box, type 'dxdiag' and then hit enter.
2 Above will appear a yellow x icon and the text dxdiag. Click on it and a window will open.
3 Check the WHQL check box.
4 If you are running a 64 Bit Operating System click on the 'Run 64-bit DxDiag' button.
5 When the utility has completed assessing your system, click 'save all information' button.
6 An Explorer window will pop up, allowing you to save your information as a text file.
7 Open that text file using Notepad (from start menu type ' notepad' to find Notepad) to review.
8 Reply to this post and while replying click on the paper clip icon above^^^^^^, click on browse to launch Explorer and find and select the text file. Then click upload.
9 The DxDiag report contains a detailed list of your system info, but no personally identifiable information.

You can also use the utility to find the details and add it to your profile.

(side note: Now all we need is to find a way to parse that data and add it automatically for each user taking a lot of guesswork out of this)...

Good job!
So, to fill out your system specs:

CPU: Intel E8400 (Note: You have this overclocked to 3.6GHz, system temps may be an issue, use CoreTemp)
http://download.cnet.com/Core-Temp-32-bit/3000-12565_4-10794077.html
Motherboard: Gigabyte EP35-DS3L (Note: for REV. level see sticker on corner of motherboard)
Memory: 4 GB (Note: Amount is listed in DxDiag but not manufacturer, timing, etc..Use CPUZ to find this info)
http://www.cpuid.com/cpuz.php
Graphics Card: 2X nVidia NVIDIA GeForce 8800 GT (Note: I do not see where your motherboard supports SLI)
http://www.gigabyte.us/Products/Motherboard/Products_Spec.aspx?ClassValue=Motherboard&ProductID=2629&ProductName=GA-P35-DS3L
Sound Card: onboard Realtek HD Audio
Monitor(s) Displays : BenQ G2400W (Digital) 1920 x 1200 &Dell E207WFP 1680 x 1050 (see notes below)
Screen Resolution: (See above)
(the rest is not critical in our case)

Notes:
The Dell E207WFP was reviewed by cnet when it came out and here is the link:
http://reviews.cnet.com/lcd-monitors/dell-e207wfp/4505-3174_7-32135018.html#cnetReview
This screen is not designed for DVD playback or gaming but as a basic desktop monitor.

The BenQ G2400W is a much higher rated LCD Monitor that includes HDMI, DVI and VGA connectivity.
http://reviews.cnet.com/lcd-monitors/benq-v2400w/4505-3174_7-32906371.html

With the motherboard and CPU you have, I do not see a need for multiple video cards, but if I was to set my system up , I would ensure that my motherboard supported SLI and that both displays were true digital displays and exactly the same. My immediate thoughts from the info provided is that the differing screens and/or cables may be having an adverse affect in your case.

To test my theory, and do this only if you are comfortable making hardware changes to your PC:

Shut down, unplug displays, remove all power, and remove (1) Video Card, leaving (1) at your highest rated PCI slot, i.e., the PCI-x16 slot. Using a quality DVI-D cable, attach the remaining card to your Benq. Reboot, Install the lastest drivers from the nVidia drivers website for your video card. Reboot. Run WMC setup from the beginning.

Is the quality of video much better in full screen mode now?

Can you describe the cables that are being used to connect each monitor now? If you are unsure, see this link:
http://www.datapro.net/techinfo/dvi_info.html
and describe the best you can in your reply.

Also, which screen are you using to view WMC in full screen mode?