It will display in 1080p because that is it's native resolution, the TV's that display 1080p in 1080i or 720p are sets that have those native resolutions but still accept a 1080p signal. If this TV is a newer model (2006 or 2007) then it will accept and display 1080p and upconvert all other resolutions to 1080p, if it's from 2005 or before then it will do the same but it will accept 1080p as 1080i and de-interlace it so essentially it will be a 1080i signal upscaled to 1080p, regardless it will look fantastic. The SXRD probably says "Full 1080p" because that is it's resolution (1920x1080) whereas the Samsung DLP is actually 960x1080 and achieves full 1080p through an effect called wobulation, in the end you still get 1080p and you essentially have the same number of pixels and there is more or less zero difference. Honestly don't worry about resolution that much even if the TV was 720p it would look awesome and resolution is actually the 4th most important aspect of a TV, color accuracy, saturation, and contrast all outclass resolution.
Now as for which to get I'll say this: look at each of them, toy around with the settings, and buy the one you think looks best. My personal opinion is go with the Samsung because I think the color is better and the picture is sharper than the SXRD and you're getting an extra 7" of real estate over the SXRD.
I saw the Samsung 67" HL-S6767W at Costco for $3,800 Canadian. It supposedly has 1080P resolution but the information at the Toshiba website is very limited. A couple of questions for anyone that can help me out. Does this television not only accept a 1080P source such as from a Blu-Ray player but does it also display in 1080P? It seems that a lot televisions that indicate 1080P actually down convert to 1080i. My other option would be the 60" Sony A2020 SXRD. It has something on the front that says "Full 1080P" so I assume it accepts and displays in 1080P. The one negative I have read about the SXRD is about the bulb burnout.