See if all u wanted to play was CS, u didnt have to install Half-Life.
If all u really want to do is play CS, dont do anything, U r fine with the patch u are downloading. Some of the big mods also let u install to CS.
Make sure u do play Half-Life though. Cracking game. Best FPS I have played. (I havent played GoldenEye
)
If u are in the UK go over to gaming.blueyonder.co.uk. Bunch of peeps ready to help u, if ever have any trouble. Make sure to play on their servers as well.