CS 1.5 died long time ago. The WON servers where taken offline, so theres no way to authenticate, If you have 1.5 just download steam and itll take care of updating. Also you can play 1.6 without steam or a cd key. Im not giving out the site cause I dont want to get banned, since it is pirated software. I used to play 1.5 but I lost my cd key, so I couldnt get 1.6. A friend from Australia game me his Half Life key so now im on CS 1.6. I dont really see any mayor differences. 2 new weapons where added. Thats about all I see since im not a hardcore player. I played CS 1.5 for a year, then about 3 months ago came on 1.6. Im not so good but I do help out. Well, most people that play 1.6 say Source looks like shit. Those who play Source say 1.6 looks like shit. Also, you could play Source off steam fro free when it was Beta with a Condition Zero CD Key off Ebay for about 15 bucks. Now that its not Beta, you have to buy Half Life 2 to play it. So Im staying away from Source. I was told that when a Flashbang goes off you go blind and only hear a ping, so you lose audio and visual ability for a while which is very realistic. FAMAS pwns for me.