Gateway FPD2185W issue

I have a Macbook pro, and I'm looking for a solution on how to use my secondary monitor digitally instead of VGA. I'm using it no on VGA now, but like everyone knows, digital looks nicer. I have the ability as all MBPs do, so I'm wondering why i can't make this happen. The problem is that the Mac will not detect it. Ill connect it directly to the computer, and yet it still wont. I know the monitor works perfectly in both VGA and Digital as i used it on my previous computer - an HP.
If any of you smart computer people could give any solutions, it would be super Great..
thanks
grant