Help me pls! HL2 install problem.

[eror]

my friend gives me a new HL2 CDKey via Email, but no CDs.

i create a new steam account, and want to register the key.
but the Steam says:" Installation of Half-Life2 Retail Standard is required before continuing. Please insert your CD/DVDinto the drive and select 'install' from autorun menu."
But i have no cds, how can i register and play the game? can i download from Steam just like "Condition Zero" and " CS1.6" ?
thanks a lot!

 

[Danimal]

lol, is that a used CD-key?

 

[eror]

lol, is that a used CD-key?

No, i believe it is new.

 

[Ranga]

theres a difference... i think the retail version cd-key is recognised as a retail version cd-key. and an online one is an online one (duh ), so it knows if ur using online or retail. so if u've as retail key, u can't download it... (that went for too long)

 

[diluted]

Go buy the game..