Going by your gamertag im guessing youv'e just got a new 360 so im guessing its a model with hdmi.
If so try connecting it up via hdmi and using that as a dvd player, I find it does a fairly good job of upscaling.
I would never advise using a 360 for DVD playback. Mine is really loud and I figure the longer it is switched on the greater the chance of it failing.
That just sounds a bit paranoid.
I've used my 360 for watching DVDs on since I got it several years back.
Much better than using a non HD DVD player on a HDTV imo.
Yes your probably right as i doubt DVD upscaling will stress the graphics/cpu of the xbox which is what can lead to failure... Still I do find the noise produced by my xbox to be unacceptable for DVD playback IMO.