Well you can get all the valve games on steam(steampowered.com)
I started playing cs iin 2000, when i was 10(lol) and i played until cs source came out. I've been playing source ever since, but i go back to 1.6 every once in a while(actually this morning i got 22-2 on aztec)
if anyone has xfire and wants to add me, my username is thecarver