I'm not 100% sure but unless you get an HDDVD or BlueRay DVD I don't think it will upconvert to 1080p. The one I have will upconvert to 1080i via the HDMI cable if thats what you're refering too, however I gots no HDTV so I can't offer you help there
These guys are very informative:
http://www.avsforum.com/avs-vb/