Will Blu-ray replace DVD? ................

It's still too early to say. In the end it's up to the movie studios to decide in what format they release their movies, so they will play a big part in the decision of which format becomes the standard for high-definition movies and the successor to DVD. The two formats will most likely co-exist for quite some time until high-definition takes over and becomes the norm.

  

What's the difference between Blu-ray and DVD?

PARAMETERS	BD	BD	DVD	DVD
Storage capacity	25GB	50GB	4.7GB	9.4GB
Number of layers	Single layered	Dual layered	Single layered	Dual layered
Laser wavelength	405nm	405nm	650nm	650nm
Numerical aperture(NA)	0.85	0.85	0.60	0.60
Protection layer	0.1mm	0.1mm	0.6mm	0.6mm
Data transfer rate	36Mbps	36Mbps	11.08Mbps	11.08Mbps
Video compression	MPEG-2 MPEG-4 AVC VC-1	MPEG-2 MPEG-4 AVC VC-1	MPEG-2	MPEG-2