You will need to upgrade your graphics card to one that has atleast pixel shader 2.0 support. Any graphics card sold today supports atleast 2.0 so anything like the ATI's X series, 2000, 3000 4000, or 5000 series or Nvidia's Fx series, Geforce 6, 7, 8 ,9 or 200 series.
paperfox already answered your question. only way to get newer pixel shader support is to buy a new graphics card that supports that version of pixel shader.
Pixel Shader 2.0 is hardware built into the video card. There is no software that can be used to emulate it.
If you want to play a game that requires PS 2.0, then you need to buy a new video card. Video card supporting Pixel Shader 3.0 came out around 2005 beginning with the Radeon X1xxx series (like the X1950) and the GeForce 6xxx series (like the 6800).