If you have the generations pack, you should have two set of cd keys. One for counter-strike and one for Halflife. You can still play by installing Counter-Strike and downloading its latest patch. If you find the halflife cd-key then you first need to download the
1.1.1.0 patch and then download and install ESF.
And Effect, if thats your cd-key, i suggest you edit your post and get rid of it before someone starts to use it and you cant connect onto won ...