I have had to reinstall Steam after it f*cked up, but now when i click to download counter strike in browse games the only way I can get it is through condition zero which I havent bought!
Have you registered Half-Life since you reinstalled Steam?
If not, go to Browse Games, click on it "register game I've already bought" and stick in your Half-Life cd-key. You may get CS back that way. If you have a CS cd-key (in case you bought it retail), you can use that as well.
Log in to your previously registered account. Your accound should contain everything you own through steam. At least it worked that way for me.
I would advice you to make a backup of all your .gcf files before you delete steam next time. This way you won't have to download any of the games you own through steam again.
The way it worked for me was that I reinstalled Steam cause the graphics got fu**ed up so I just double clicked counterstrike and the other stuff I got.