Advantage of DVI input on monitor

Hey all. I recently bought a new HP wide-screen monitor and it has both a DVI input and VGA input. So, I have a regular VGA cable, but I think I need an adapter that goes from VGA to DVI-D.

Well, first of all, whats my advantage of going from VGA to DVI? Should my monitor look at lot clearer is it not worth the money to get the adapter?

Secondly, my brother just told me that I can't buy an adapter that goes from VGA to DVI-D. So, is it only possible to buy a cable that goes directly from the adapter on my video card (ie. DVI-I) to my monitor (DVI-D)? If so, how much would one of these cost?

Jam it back in, in the dark.

Well my video card only has DVI-I inputs, while my monitor has a VGA and DVI-D adapter. However, what you are telling me is that even though I have a VGA cable with a DVI-I adapter going into my video and a VGA adapter into my monitor, there shouldn't be a difference if I slap on a DVI-D adapter onto that empty VGA and plug it onto the other plug in my monitor or just does it depend on whether or not I notice the difference. Also, should there not be a difference between the suggestion that I said above (ie. VGA cable with DVI-I adapter and DVI-D adapter), or would I be better off getting the standard DVI-D cable (note that money is not a problem with me).

Sorry if I am confusing you, but I just want to clarrify.

There's nowhere I can't reach.