Ok, three points:
It's only $10 + tax. I understand, and am, a freebie person, but hl is a good game and doesn't q3 cost something? Trem is free because is became a stand alone.
As far as os support goes, Windows is a great operating system. ... Just with better f'ing crackers and virus coders; and I've seen a windows environment simulator on linux and have heard of such programs for Mac.
The only real hinderance is you need high speed internet to download both Trem and NS and I have a 28.8k modem that rarely gets up to 28.8k, and in accordance with the degrading comments from our New England sized UK friends, a good part of the US is on dial-up still. Thankgod for wireless on campus.