The thing with counterstrike is if you're a "hardcore" player then getting the game setup to your preferences is very important.
Playing CS 1.6 on anything above 640x480 ruins my game, changing the resolution completely changes the feel of the mouse, the amount you have to move the mouse across the mat to achieve a 360 degree movement increases and the sensitivity feels different.
I started playing CS back in 2000 and played with 640x480 ever since.
I turn on AA because on a flat widescreen monitor at 640x480 the players heads are too jagged and since this is what you're primarily aiming at smoothing the heads over was a must.
It's one of those things if you're one of those serious CS players, gota have the right mouse, the right mouse mat, mouse skates and mouse bungee's, the right headset and the right resolution all of which is going to be different from person to person.