W3bby, yes, you will get a smoother picture for motion with a 24p, 48p or 72p setting, its not the same as the blur problem, its the smoothness of panning if the refresh rate of the display matches the source (ie. no repeating of frames like 3:2 pulldown to make up the difference in the refresh rate).
I see the 1080p/24Hz, 1080p/50Hz, 1080p/60Hz for HDMI inputs, but I'm sure that is for video signals not PC signals. You can have problems when the projector detects that a PC is connected which it does when it first connects through the EDID HDMI protocol, the PC will tell the projector what resolutions it supports and sometimes this does not work properly. What I'm worried about here is that the projector does not recognise the HTPC correctly and won't switch to one of the resolution settings. With my current projector it won't recognise the PC unless the PC is switched on first.
1080p24 is a must for Blu-ray sources and 1080p72 would be nicer but I don't think it makes a difference as the projector processor will simply show each 24p frame 3 times at 72p, which as it is the same multiple for each frame you wont get the judder like you do with 3:2 pulldown. Link: http://www.avsforum.com/avs-vb/showp...09&postcount=7
Also, you mention the use of HDMI in your setup. Do you use a HDMI video card or do you use a HDMI cable converter (as these can make a difference to EDID problems). What video card do you use?