What brand and model is the monitor?
We can check if it can't run 640x480 resolution or has some other limitation.
Some video card/monitor combinations might have problems with 640x480 resolution, and though I don't know of any monitors that can't display 256 color graphics, I suppose it's possible there could be one.
Also the QuickTime 2 that came with Myst from 1993 might be an issue on XP.
Another way to run Myst is to use ScummVM.
Myst, Myst Masterpiece, and Riven are listed as running on ScummVM.http://scummvm.org/compatibility/
Download and install the latest version of ScummVMhttp://scummvm.org/downloads/
The files you need to copy from the CD to a folder on your hard drive are listed herehttp://wiki.scummvm.org/index.php/Datafiles#Myst
After copying the files to your hard drive, start ScummVM, choose the "Add Game" button, and browse to the folder where you copied the Myst files. ScummVM should recognize the Myst files and add Myst to the ScummVM menu. You should be able to start the game from there.