ssd in macbook runs only at 1.5 gigabits

Hi, I have a macbook Mid 2009 (white) it runs Mac OS X 10.6.8 (10K549) recently instale it a new SSD disk on the place for the HD, It is a Kingston 120 gb ssd now v+ 200. I have a problem it runs only ant 1.5 regociated velocity, and the max speed for write and read its a round 120 mbs per second, could you help me to increase the velocity arround 3 gigabits?

NVidia MCP79 AHCI:

Fabricante: NVidia

Producto: MCP79 AHCI

Velocidad de enlace: 3 gigabits

Velocidad de enlace negociada: 1,5 gigabits

Descripción: AHCI Version 1.20 Supported

Thanks for your help.