I'm in need of some advice from fellow laptop users.

I have a laptop and would like to buy and plug an external 120hz screen to it, but problem is that my laptop only has VGA, HDMI and USB ports. However I heard that neither VGA or HDMI support 120hz so the question is, will the 120hz work if I bought some vga->dual link dvi adapter? I ask this because I'm wondering if there are some technical difficulties that would prevent this from working.