and available here: http://www.mektek.net/mtx/beta/SetupMTX1.0.1.7.exe
after installing you need to right-click mechwarrior 4 in the MTX downloader and "check for updates" this will upgrade the new free game to .20 version with is free without the cd check.
not sure why the beta tag is there but the download page is here: http://mektek.net/projects/mw4/download.html and leads to that exe