Nimbus

i was at a friend's place. he had a ~60" rear projection crt. a computer was hooked up to it through dvi. the computer was set to 1080 resolution. he played trailers from msft/apple that were in both 720 & 1080 format. he played both versions of a trailer and didn't tell me which one was which resolution. i couldn't tell a difference.

can you tell a difference between 720 and 1080? what was the setup (display, source material)?