Re: Upgrade from Windows 7
Screens and monitors are simply output devices and have no effect on bootability.
Not quite 100% true, but I have given you an upvote.
Although it's been a while since I've seen this, some machines want to output an error message when they dislike the screen only the screen won't show it. And many screens I've known - while they have a or DVI input, they won't do text mode in any form and very rare graphical modes, thus you cannot see a boot menu or other such things (eg the WIndows installers IIRC all the way to Win7 and many *nix installers start in text mode till you do some of the installation or select a waiting menu option).
In short - yes the machine could probably boot happily as you say (but a few won't), but you may not be able to use it.