Quick question regarding my PS3 and Samsung TV

[Facade19]

Hello all, I just registered right now.
I am sorry if this has been discussed already, but I am just a bit confused here.
I just recently purchased my PS3 (Wednesday) and want to try out a Blu Ray movie (kingdom of heaven).
However I came across at a different forum (gaming forum) that if your tv does not support 1080i/p then the movies will get down converted to 480p.
My tv is the Samsung LNR26W, which supports 480i/p, 720p and 1080i.
Its native resolution is 1366x768 however.
I have my PS3 hooked up to my tv with a HDMI cable.
And have my PS3 hooked up with an optical cable to my sound system (logitech Z-5500).
When I purchased my HDMI cable, my PS3 automatically set itself up to 1080i.
When I play my video games the video content is presented in 1080i.
I know it because my 360 is set up at 1080i as well and the picture quality of Resistance looks extremly similar to my 360 games when displayed at 1080i.
Now I am wondering if I was going to purchase Kingdom of Heaven, would the movie be displayed at 1080i or 480p?
Because I just tried out the standard DVD (the Last Samurai), and it was shown what I believe to be 480i. The PS3 actually down converted the dvd.
And once again I am sorry if this has been already discussed it is because I am worried.
Thanks for any help.