All depends on your budget and what you want to do with this computer.
THat is a very old graphics card and processor. If you upgrade your graphics card, you would also want to upgrade your processor. We would need to know what motherboard you have to know what CPUs are supported; however, your money would be better spent on a whole new motherboard + CPU combo.
What is your budget and what games do you play? Also, what motherboard and power supply do you have?
No. You do not need to change your graphics card. The question is, do you WANT to change your graphics card. If you do, then we would need to know the full system specifications, to include the motherboard model number, the power supply model number, and your upgrade budget. Once we have that, then we can make some recommendations.