Question regarding Pixel Format/Color Range on new LG 60PM6700 Plasma TV (1 Viewer)

I sent the below questions off to LG but the response I received was to "Use the Picture Wizard"... which of course answered none of my questions.
I'm currently using the THX Picture Mode on my new LG 60PM6700 Plasma HDTV with my HTPC set to YCBCr 4:4:4 setting in Full Range (0-255).
My video card is a ATI 5870 in a Windows 7 x64 with 8 gigs ram running on a i5-2400 cpu.
I've had issues with blacks and greys being washed out and blocky so after some research I decided this was because of my ranger/pixel settings.
I did some experimenting and the mode I have it in right now is working fairly well but I would like to narrow it down to what the best combination would be.
Unfortunately I can't seem to find much information on exactly what my TV is expecting to be sent to it in the various picture modes.
This is the email i sent to LG:
I recently purchased a LG 60PM6700 and I am trying to calibrate the screen to have the best picture quality.
I currently use a computer as a HTPC (Home Theater PC) connected to the LG 60PM6700.
What I need to know is the proper Pixel Format and Color Range to use for this model TV?
If I could get documentation or answers to the following it would be great:
1) Does this television expect a color range of 16-235 or 0-255?
2) Does the "Picture Mode" have any effect on what color range the TV is expecting? If I choose THX mode does that want 0-255?
If I choose Standard does that want 16-235?
3) What Pixel Format should be used with the TV? I can choose from the following:
Ycbcr 4:4:4
Ycbcr 4:2:2
RGB Studio/limited
RGB Full
4) Does the "Picture Mode" being used effect which "Pixel Format" should be sent to this TV?
Does "THX" mode expect Ycbcr for example but Standard may expect RGB Full?
I apologize in advance if this has already been answered, I was unable to find any specifics and I am fairly new to this level of tinkering.
Any help or direction you could give would be wonderful.
Thank you in advance.

hi
First, when ever you have issues, GET RID OF THE VARIABLES (meaning the HTPC), until you get things figured out, then introduce the variables of your HTPC.
Video is 0-255 with black being defined at 16 and white being defined at 235. The picture mode selected should not matter (unless a PC mode, which may signal the display to expect black as defined at 0).
I would try either of the component signal outputs or the RGB limited.
Fun stuff!

Hi Marc,
Your 0-255 setting is the problem. Change that to Limited or 16-255 and your blacks should look a lot better. However, the new LG plasmas, yours and the flagship 9700, do not have the best blacks to start with.