Go to the Magnavox site and look up your set, or do a search on the net for the model number.
I found a spec sheet at: http://www.annunci-qui.com/14/posts/16_Annunci_Audio_tv_foto/103_televisori_e_proiettori/461_MAGNAVOX_50ML8105D_50.html
This set will only work up to true 1080i. It will not work in true true 1080p which is the full HD mode. They don't say it clearly in the specs, but its 1080p mode is an up-converted mode. The cable or satellite box has to be able to handle 1080 modes. For normal viewing in HD this set should be visually very good. Only a Blue Ray DVD player and some other types of gadgets are able to put out a 1080p video signal.
Cable and satellite services are normally in 720i, some are in 720p, and a few specialty feeds are in 1080i. Most satellite and cable TV boxes cannot support anything above 720i.
The lamp life is 4000 hours. The lamp is fairly expensive to replace. I would seriously consider to upgrade to an LCD or Plasma display. The new generation of TV sets are far superior to the DLP types. Whatever type you choose, make sure it can work with true 1080p.
Go in to some of the show rooms and compare a projected type TV (if they still have them) to a true flat screen. All the projected type screens can never achieve the sharpness and aspect ratio accuracy of a flat screen set.