Me and my fiance just purchased a Sony 55" Grand Wega (KDF55E2000). It supports 1080i but has a native resolution of 1280x720. We were at a few stores and the picture looks unbelievable especially for what we paid but my only concern is right now I have a 1080i tv (with no 720p support.) My current tv is a 42" Mitsubishi RPT which supports 480i, 480p, and 1080i. The new tv supports 1080i but it downconverts it to 1280x820. Is this an upgrade or am I going backwards?