I accidentily hit the OK on the "Optimizing Media Center" after selecting TV and S-Video - it really dimmed everything down to barely readable.  Is there a way to go back and undo the auto changes?  I went into the nVidia control panel and tried to make some adjustments but nothing seem to improve the display.

Not that I know of.

This "feature" has annoyed me on many occaisons also.

The best workaround IMO is to change the settings back to monitor or flat panel and apply that to get the brightness and colors back to normal. I then edit the registry to enable Media Center's overscan compensation and manually tweak the overscan levels for my particular HDTV.

I don't know why Microsoft bother's tweaking the brightness/contrast/colorspace for whenever an HDTV is selected in the MC TV setup. Every single video card on the market today automatically transforms the standard PC's sRGB colorspace into YCbCr with a BT.709 colorspace whenever an HDTV with an HDMI port is used so the only thing Media Center needs to deal with is overscan.

FYI, to manually tweak the overscan:

http://blogs.msdn.com/astebner/archive/2006/04/29/586961.aspx

The values I use for my particular 50" Toshiba HDTV are (I save the following as MCE_Overcan.reg and then double click it to install if I ever re-install the OS. This works for MCE2005 and Vista but I haven't confirmed Windows 7):

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Media Center\Settings\MCE.PerUserSettings]
"marginLeft"=dword:00000028
"marginTop"=dword:00000002
"marginRight"=dword:0000001c
"marginBottom"=dword:00000002
"marginSaved"=dword:00000001

Thanks, I will take a look at that!

HT Slider:

Not that I know of.

This "feature" has annoyed me on many occaisons also.

The best workaround IMO is to change the settings back to monitor or flat panel and apply that to get the brightness and colors back to normal. I then edit the registry to enable Media Center's overscan compensation and manually tweak the overscan levels for my particular HDTV.

I don't know why Microsoft bother's tweaking the brightness/contrast/colorspace for whenever an HDTV is selected in the MC TV setup. Every single video card on the market today automatically transforms the standard PC's sRGB colorspace into YCbCr with a BT.709 colorspace whenever an HDTV with an HDMI port is used so the only thing Media Center needs to deal with is overscan.

FYI, to manually tweak the overscan:

http://blogs.msdn.com/astebner/archive/2006/04/29/586961.aspx

The values I use for my particular 50" Toshiba HDTV are (I save the following as MCE_Overcan.reg and then double click it to install if I ever re-install the OS. This works for MCE2005 and Vista but I haven't confirmed Windows 7):

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Media Center\Settings\MCE.PerUserSettings]
"marginLeft"=dword:00000028
"marginTop"=dword:00000002
"marginRight"=dword:0000001c
"marginBottom"=dword:00000002
"marginSaved"=dword:00000001

This may help me with a problem i'm having. I'm assuming the dword values are hexadecimal but I can't see a pattern in your values to figure it out myself. What value represents 1 pixel or percent of overscan so that I can tweak my settings. Also what bearing does the margin saved have, does a 1 at the end save the setting where a 0 wouldn't?

Droid6:

This may help me with a problem i'm having. I'm assuming the dword values are hexadecimal but I can't see a pattern in your values to figure it out myself. What value represents 1 pixel or percent of overscan so that I can tweak my settings. Also what bearing does the margin saved have, does a 1 at the end save the setting where a 0 wouldn't?

Each value is the number of pixels in hexadecimal that the graphical user interface should be brought in from that side.

The "marginSaved" value turns on (1) and off (0) the overscan compensation feature for the GUI.

BTW, for those of you wondering: Why not simply adjust the video card settings to get rid of overscan? The reason is simple: Optimal image quality.

HDTVs are typically optimized to display 720p or 1080i/p video formats. In order to take advantage of this you need to send a native 720p or 1080i/p video format to the HDTV. Since all video content, from movies, TV content, DVDs, etc. are mastered with the anticipation that the outer portion of the image is not viewed, TV manufacturers design their HDTVs to produce a compliant amount of overscan and spend a lot of time tweaking things to optimize the image for a 720p or 1080i/p signal.

So, in general, the best image quality form your seating position can be had by configuring Media Center to use 720p, 1080i, or 1080p as the output format and using a color calibrated HDTV, complete with a small amount of overscan. This requires Media Center itself to shrink the GUI in order that GUI elements are not hidden by the overscan.

One option that some use for Bluray movies is to disable overscan on a 1080p HDTV. This produces a 1:1 pixel map (assuming Media Center is also outputting a spec compliant 1080p) and some argue this produces a slightly sharper image. I'm on the fence with this one because while in theory I 100% agree, in practical tests where I have tried this, I always find the smaller image (complete with visible overscan that is intended to be hidden) produces less detail within the actual movie. In the real world, the best movie experience seems to be to use the default overscan settings on the HDTV and to always send the HDTV 1080p (if it accepts it). If you do this, you then need to tweak the registry entries provided in my last post if you want the Media Center GUI optimized for your particular HDTV.