HD-DVD is now officially halted. However, this article is still contains information on HD-DVD, and its comparison to Blu-ray for historical background, as well as the fact that there are still many owners of HD-DVD player, and a period of time, HD-DVD players and discs will be sold and traded continuously on the secondary market.
Up to now, both Blu-ray and HD-DVD player manufacturers made their units be able to playback standard DVDs which is expected to continue with Blu-ray Disc players, but now HD-DVD has been halted. This means your current DVD library is playable on either a Blu-ray Disc or HD-DVD player. Even if you play a standard DVD in either a Blu-ray Disc or HD-DVD player, you can watch it at standard DVD resolution or have the player upscale the DVD playback signal to match 720p/1080i and, in some cases, 1080p mode that will be a better match for watching on an HDTV.
As for the standard CDs, most Blu-ray Disc and HD-DVD players will play standard CDs/CD-R/RW discs. Yet, there are some exceptions to this, including the first generation models from Sony, Pioneer, and the LG BH100 Blu-Ray/HD-DVD combo set. If you desire CD compatibility, be sure you have read the specifications or information on a brochure of the model that you are intended to buy.
Actually, you needn’t to buy DVD player hardware, just download a DVD player from internet and install it on PC; you can easily to play all DVDs.