HOw can i overclock GeForce 7500 LE GPU ???

i have a GPU nVidia GeForce 7500 LE and i want to overclock it since i have overclocked my CPU but i dont know about GPU overclocking ... if anyone can tell me in a few words what programs i need exeprt ati-tool and riva-tuner since i have them and in steps what i must do ...

here are perfomance specs:

memory : 256MB of dedicated video memory, however it also supports TurboCache, giving it up to 512 MB of video memory

core clock speed: 550 MHz

memory clock speed: 263 MHz (526 MHz effective)

Graphics Bus: PCI Express and AGP
Memory Interface: 64-bits
Memory Bandwidth: 4.2 GB/s
Fill Rate: 2.2 billion pixel/s
Memory Type: DDR2 with TC

and here is a pic fro GPU-Z :