LCD resolution

[BTRY B 529th FA BN]

i just picked up a Samsung 214T Lcd. I bought this because i finally realized it was my crt giving me headaches (19" Sony G400) I realized this when i cross checked my headache problems by trying his VX922 (swEET LCD) So, naturally i went for exactly what i wanted when it came to something that doesn't get outdated as fast as intel cpu chip. I am happy with it, even with a tiny pixel dead in the lower rigth corner, which is WAY out of the way of where my eyes naturally fall when looking at my screen. The question i have is this. At 16x12 my games play smooth (75.4kHz/ 60Hz) I recently tried my game at 800x600. (46.9kHz/ 75Hz) same map same everything and it looked more jumpy/jittery. i am thinking it is becaue of the refreshrates. Could it be that? and why does it have 2 rates (kHz/ Hz)???

thanks,

BTRY B 529th FA BN