Question : Converting latitude and longitude to cartesian coordinates on a conic map

I've been wringing my hands for a few days now, because I've got a doozy.

Dig this map:
http://www.mapresources.com/zoomify/zoomify.asp?folder=USA-XX-894923

I believe the correct term for this type of map is a Conic projection. I know that a Miller Map projection is more ideal in this type of scenario since it's latitudes and longitudes are parallel. I'd love to use a map like that but I'm limited to ones I can buy that contain accurate congressional district maps.

I also have a large database of points with corresponding zip codes. I need to plot these zip codes on the map according to their latitude and longitude (which I have).

Answer me these questions 3:
1. Do I have all the necessary data to do what I'm attempting? I think I may need a beginning reference point for the map but I'm not sure what it's called or even what to ask for.

2. Assuming I can gather all the necessary pieces to this puzzle, what is the formula for the conversion? It would be keen if it was a PHP function returning XY values, but that's just going above and beyond.

3. If all of this is a fool's dream, is there a place where a miller projection of the US Congressional Districts can be purchased?

Answer : Converting latitude and longitude to cartesian coordinates on a conic map

I have to leave soon, and I won't be able to research this to run it to ground.  What you want to do is 100% possible with Google Maps.  You could combine an HTML imagemap with a Google Static Map and create a map with clickable links that present their XY coordinates to the action script.  The script, in turn, can know what map tile was displayed and where the click was located.  The rest is just a data base lookup.

Google can geocode a ZIP code.  It's fairly accurate, when you consider that a ZIP code is not a place, it is a postal carrier's route.

Maybe if you describe the application from a 50,000 foot level, there will be a better way to skin the cat.  I do not know of any symbol you can put 15,000 on a screen and still be able to read much.  What's the application supposed to do (without describing it in terms of the technology)?