If you can already change weapons with your mousewheel without the extra mouseclick, you will not need my "fastdraw"-script. And since it only works for the mousewheel, you definitely need something else for the "fastdraw" on the keyboard. This is what you need, if my memory serves my right:
Edit your config.cfg (with notepad or whatever) in your "cstrike" folder (Counterstrike folder if it is the retail edition). Add this sentence:
hud_fastswitch "1"
Remember to save and exit before you test it.
If you do not want to edit your files, then you can bring down the console, in game, by hitting the tilde key, and then you have to type:
hud_fastswitch 1
This should take effect the second you hit the enter key.
Either way Countersrike should remember this setting for future games, thus it is a one time configuration.