I don't believe this to be the case, no. I also don't believe that Kevin's statement about losing blacker than black with the 990's DVI switching is correct, since the switching is not directly affecting the signal at all.

DVD players that have DVI or HDMI outputs should be preserving the digital video data all the way through to the display. Most also convert the 480i video contained on the disc to 480p, 720p, or 1080i (some HDMI players support digital 480i output, but most don't). Whether it is better or not depends on how well the conversion is performed.

VGA is an analog format, whereas HDMI is digital only and the full DVI standard allows for either analog or digital (DVI was originally developed to connect PC's to LCD flat panel monitors, which are digital display devices.)

From what I understand, it depends largely on the source device being used. A good progessive scan player with component output to a good, properly calibrated display (particularly a CRT, which is an analog device) could yield results equal to a mediocre implementation of DVI or HDMI when connected to the same display. I'd recommend looking at your specific case, keeping in mind that at some point we are likely to see high definition video sources restricted to using digital video outputs (primarily HDMI when that day comes) - with analog component or VGA outputs restricted to a maximum resolution of 480p.