Time to upgrade your video card. In fact, it may be time to upgrade your entire PC.
Video cards with pixel shader 3.0 came out in 2004 starting with the nVidia GeForce 6xxx series (6200, 6500, 6600, 6800, etc). ATI released their pixel shader 3.0 cards in 2005 starting with the Radeon x1xxx series (x1300, x1600, x1900, etc).
If you want to play games where you generally do not have worry about upgrading, then it's best to buy a console for games like the PS3 or Xbox 360.