no, this isnt bootlegg or anything of that sort, you can get it STRAIGHT FROM STEAM untill September 20th.
i already have downloaded it, it only took about a half hour to get and install, you DO however need to register with steam and download their platform, but whatever... i already had an account to begin with.
this is the FULL game, complete with the acheivements and all the fixins.
so if you DONT have it head over to:
http://store.steampowered.com/search "portal" and it should lead you from there, it WILL say theres a price untill you click on the link for portal, then it will show you the freebie link