Well I use steam for all my games on windows.
When it works its great, but sometimes it goes do lally and takes about 1-2hrs to wake up and sort it out.
I've got a free copy of portal on my account at the moment which I could give you if you want. (I brought portal 2 pre release which included a free copy of portal)
For certain you have to be lost to find the places that can't be found. Elseways, everyone would know where it was