I'd expect any monitor or video card labeled "HD" to also support HDCP over DVI, which older hardware doesn't. And you'd need that to play Bluray content.
I agree but some videocards have HDMI outputs which will connect directly to an HDTV or an HD monitor with HDMI imputs.
other monitor inputs are dependent on your videocard.
FordSVT a computer has a BD-ROM drive. It happens to be able to also play BD-Video.If you have a Blu ray player in your computer it will certainly display Blu ray movies, otherwise why would they put it in your computer?
With the ability to add firmware updates to a standalone BR player I'd suggest saving up for one that has BD-Live Profile 2.0 as you can get a lot more content via the Internet and have less issues with new discs that have newer DRM software.
If you are purchasing a new computer monitor consider getting one with HDMI inputs.