I have learned tons these last two days.
So far today is the third day after connecting my HTPC for the first time to my 57S700 Hitachi RPTV.
I have a perfect desktop image of 920x500p. Direct from Powerstrip:
PowerStrip timing parameters:
Generic timing details for 920x500:
HFP=104 HSW=80 HBP=80 kHz=34 VFP=20 VSW=1 VBP=42 Hz=60
Linux modeline parameters:
"920x500" 39.996 920 1024 1104 1184 500 520 521 563 +hsync +vsync
and I use 1920x1080i for DVD playback and so far it's looking very good;
Generic timing details for 1920x1080:
HFP=169 HSW=56 HBP=295 kHz=34 VFP=2 VSW=5 VBP=38 Hz=30
interlace +hsync +vsync
So far I have learned (from Karnis-I am cut and pasting);
All 1080i/ 540p based timings (that are safe) have a scan rate that is exactly 33.75KHz, refresh rate is 59.94Hz(or 60) and vertical line total is 563 (this value must be exact! I just forget why...it's because if your vertical line total varies just a bit from this you will loose sync. Keep the progressive vertical line total at 563 (interlaced 1125).
for all resolutions.
BE AWARE THAT NO TWO MODELS OF HDTV WORK EXACTLY ALIKE. FOR EXAMPLE, MY MITS LIKES TO SEE A SCAN RATE OF 33.75KHZ, WHEREAS SOME MODELS, LIKE HITACHI, PREFERS A SCAN RATE CLOSER TO 33.5KHZ. IF YOU HAVE ISSUES WITH ONE SCAN RATE, TRY THE OTHER.
I have found this on karnis' very long thread,