Display Dims During Video Streaming Content

I'm having a problem that if I am watching streaming content, XP
Media Center is dimming my display, hence the video is gone. The content
keeps play, I can hear the audio. What I have to keep on doing is either
moving my mouse slightly or depressing the volume +/- button on my Microsoft
Media Center Remote. Then the video comes back on. This keeps on happening
every 20 minutes. The only way around it seems to turn off power management
for the Dell 2405 FPW monitor on my XPS600. That is a burden, since then after watching, I would have to
turn it back on again each time.

What I don't understand is that the PC is not really inactive - there is
video playing which is using CPU cycles and there is audio as well. I can't
find any setting within Media Player that will allow it to play without this
interruption. I did find the check box that allows the screen player to be
turned On or Off during video playback and it was "Unchecked" - so the video
is not interrupted by the screen saver.

Is there a setting I'm missing here to allow the video to continue to
display on the monitor without having to diable "Power Management" for the
monitor each time?

Thanks,

Roger