this site's downloading script

this site's downloading script

i was trying to develop a php script that will work just like the one on this site: instead of direct downloading, it redirects the file and allows you to put the download count this way.
so far i've found a way to do this, however every time i download a w3x or w3m file its md5 doesn't match with the original and it wont load.
i believe that the problem is the content type since don't know which is used for warcraft maps (the one i tried is application/force-download).
i would realy apriciate if someone could post a part of the current download script or just tell me what content type should i use.

thanks in advance

What exactly are you trying to do, make a download system for your site?

exactly
i've done this a couple of times and it worked fine for exe, zip, jpg etc.
but from some reason the downloaded w3m and w3x files are always corrupted.