Originally posted by TURBOV6
You may not have to install the orig half-life, but you do need a valid serial key. Beta version will end soon and then the 'official' release will be out, but the way steam works, they can constantly push new updates.
They will not sell on CD. Just buy the original Half-life or counters-strike retail ($20 or so) and download steam. Valve is setting themselves with a new business model using Steam, so this game, now, is really just a test bed.
Can't wait till Halfe2 comes out, with hopefully, a CS2.