ok first, download ATI Tool from here
alright, after you install the program, make note of the clock speed that is default. you wont have to remember these because it saves it in its own profile under default to restore if anything goes wrong.
ok, what i did when i had my x300 desktop version was go into the settings of it and change apply overclock after moving slider or something like that.
open the 3d demo tab and there should be a cube thingy spinning around.now to overclock, start with the core and move it up in 5 increments making sure to note that on the 3d demo, no spikey things are sticking out because that is artifacting. after you go up like 20MHz, try the memory clock. 5 increments also, if not avaible, just go up in small increments.
again make sure NO artifacting. also let it run at the overclock for awhile and then feel the bottom of the notebook where your gpu is. make sure this DOESNT get TOO HOT!
after you found the highest overclock without artifacting, just let it run for a couple minutes.
warnings... the desktop might blur colors if you have gone to far. lower the clock, and re-apply your desktop wallpaper and it will be fine.
the only way to see if this truely can help performance is in bench marking and in gaming. download 3d Mark 05 and let it run at your default clock. (*oh, dont forget to save your high overclock in the profiles tab er something*) and then run it at your overclock. MAKE SURE YOU HAVE THE LATEST DRIVERS FROM ATI. download catalyst 5.6 er something and everything will run smoother.
gaming...download fraps or use the console command to show the fps. run the game at the default clock and make note of the average fps you see in the corner. now load the overclocked profile and now run the game. making note of the average fps in the corner.
congratulations! if you did this correctly, you have overclocked your laptop. post if you have any questions.