I have just installed the game from my two dvd's and want to play the game. I have a very slow internet connect and therefore really can't way 3 days for a 15GB game to download. When I load the launcher it tells me to insert the CD key which I do, then it says "Checking for updates". After this it tells me to install downloader.exe which then tells me to install the Enhanced Edition patch.

Can I disable this and just try the game from a fresh installation without patches?

Thanks.

Of course! I suggest that you patch the game up to 2.1 version (patches can be found here http://www.thewitcher.com/support/ .
This way you 'll have a very stable and well balanced game and it won't take you countless hours upgrading. I actually prefer 2.1 edition to the EE!