THIS IS NOT WAREZ. YOU NEED A VALID STEAM ACCOUNT WITH CSS ON IT OTHERWISE YOU CAN'T PLAY.
This contains the gcf files in which valve stores gamedata.
Download it here, 1.76 Gigabytes
Once it is downloaded,extract it with 7zip/winrar.
Close STEAM.
Take the steam folder from the archive, and overwrite your current steam folder (Its just adding files) If it asks to overwrite the steamapps folder, let it.
Run steam.
CSS should be fully updated and ready to play.
This will be so until Valve updates CSS. Then you will just do this and be 99% updated xD
Hope you like.