Comp Techs...need some help

Hey All, 

looking to make some computer upgrades and needed some help from the guys out there. 

I have a Gateway FX7020 :

    * AMD Phenom 9600 Quad-Core 2.30GHz Processor
    * 2MB L2 Cache, 2MB shared L3 Cache, 3600MHz Bus
    * NVIDIA GeForce 8800GT
    * 500GB (7200RPM, 16MB Cache) SATA II Hard Drive
    * RAM: 3g DDR2 SDRAM

and have two 22" HP monitors. 

What I would like to do is get 2 more 22" to my current set up...so total of 4 22" monitors. 

is there a way to get two video cards in my comp? I am not looking to stretch the desktop over all four monitors...meaning if i max display a program I want it to only fill that one monitor its on rather then all four. 

Thanks for the help!!!