From your link:

Resolution Support: 640x480 (35 kHz Horiz. Scan, 66.7 Hz Vert. Scan)

Click to expand...

The PC is undoubtedly putting out a 60Hz Vertical Scan rate flavor of VGA, so it's not likely to work without a lot more flexibility on that end than the average VGA card possesses. If an Apple CRT isn't multiscan or a unique model like the 12" 'zaToppers or the Portrait, they aren't really worth keeping around as far as I'm concerned, but I'm a 24bit TPD junkie.

Just about any multiscan VGA CRT or LCD will be better suited to your cross-platform needs.