You appear to have an AGP-based motherboard so you'll need one of those for a start.
Why do you feel you need a better card? Are you going to be playing the latest games, for instance? What's your budget?
Tell us your system spec. Mainly CPU, motherboard (make & model), memory, operating system & power supply (PSU) rating in watts. If you haven't a clue download, install & run the free Everest click here. For the PSU you'll need to open your case & have a look. G
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