BluRay discs (from what I have read) would only work on BluRay players, on which HD-DVD and normal DVD would not play - so you would need to have two players : a BluRay player and a DVD player...
This is not correct, BluRay players will play normal dvds and most probably upscale them to near HD quality.
I believe Toshiba have also made a BR & HDDVD player combined already.
BTW, Blu-ray is the way forward!
Movie studios supporting the Blu-ray format include: Sony Pictures/MGM; Disney; 20th Century Fox; Paramount; Warner Brothers; Lions Gate Home Entertainment; and Eagle Rock Entertainment. These companies combined for 90% of the DVDs sold in 2005.
EDIT:
BluRay will do DVD & upscale example:
Sony's First Blu-ray Disc Player
The BDP-S1 features 1080p (1920 x 1080) full HD-video output for brilliant HD imagery and upscaling of regular DVDs to 1080p output. It sports a sophisticated design and exceptional build quality with rigid beam construction, as well as finely tuned audio and video parts and circuits. The player offers HDMI output and advanced digital audio support, including MPEG-4 compression compatibility.
http://www.amazon.com/gp/product/B00...&s=audio-video