first, are you SURE this monitor can scan down to 15 Hz? the page you gave says on the specs that it is Horizontal 28k - 80kHz; Vertical 48 -75Hz...
The P-IV has a buldin Scandouble-Fickerfixer, so no proplem with a PAL/NTSC screen.
BUT both cards serve at he same time graphicdata to the monitor, so autosensing could be a problem.