Cool! its a paper model!
I've never built one of these before, but it looked so cool I had to give it a try.
You can download a free version that just has the towers and the base, or opt for a $4.95 download of the entire complex (except WTC #7) at http://www.fiddlersgreen.net/
All you need to assemble this is a color printer, scissors, and glue. I have some art supplies here so I did things a little more professionally, so to speak. I'd recommend you use a sharp xacto-type hobby knife with a new blade, and a rubber cutting mat. I used rubber cement to glue it together but elmers glue would probably work just as well.
I have a printer that can print on wide paper, so I scaled the printout to fit onto 11x17 Hammermill card stock I bought at Staples. A steel straightedge ruler is a very very good idea to cut straight edges and also to score the paper along the fold lines. I also got a piece of foamcore board to mount the whole thing to.
A couple of nights and some gluing and cutting, and you'll have a neat model you can display. Its fun and therapeutic at the same time.
Very cool. Its about 1:1171 scale. If I wanted to build a scale model for my N scale train layout, by the way, the towers would be 8.5 feet tall!