Yeah, I didn't think to mention the hood, headlights, bumper. Which you would need all of. But you would have to change the rad. core support, or at least the sides of it that house the headlights and tie the corners together.
http://www.hondaautomotiveparts.com/...13S5A0_B49.gif Either parts 36 & 37, or ass'y #10 in the diagram. Sorry it wouldn't let me paste the image so I had to put a link. This is at hondaautomotiveparts.com if you want to go there and look up prices. #10 is about $160, #'s 36 & 37 would total about $35, plus shipping of course.
As far as difficulty goes, you would need a welder and welding skills, as these are all spot welded together. If you have those things it would probably be pretty simple.
BTW, I have also heard of people just forming the metal to accomodate the different shapes of the 04-05 front end, but I wouldn't try it myself for fear of having badly spaced body lines, or just a junky looking car.