You Don’t Need The Brushes Palette To Change Brush Size
In Photoshop CS2 you can increase or decrease the size of your brush by 10 pixels by pressing the Left or Right Bracket keys when the Brush tool (B) is selected. Once your brush is more than 100 pixels in size, it then moves in 25-pixel increments; if you go higher than 200 pixels, it moves in 50-pixel increments until you reach 300 pixels, at which point it moves in 100-pixel increments.