I dont have half life!
I have Counter strike:CZ!
Can i play Natural selection?
If you can help plzzzzzz do it!

No, I don't believe you can. I'm pretty sure CS:CZ only gives you access to Counter-Strike and The Counter-Strike Source Beta, not Half-Life. You can not install Natural Selection with Condition Zero.

You actually bought CS:CZ? Gods....

No, CS:CZ uses a modifed half-life engine, you will NOT be able to install ANY mods.

buy HL via steam or go to the store and get yuor self a copy of it.

Well if you have a steam account there -is- a way to get halflife working for free... but can't go into that here, its not exactly erm...legal... do a search on google

and get banned, ask voogru (one of the NS Devs) what happens when your friend hack a copy of CS:CZ onto your account.

You can find old versions of HL in bargin bins at Kay Bee some times...all you need is that CD Key. My friend found an old-**** version of it there for $9.99.