Computer help please

hi, i hope this is the correct section to post this, but i was wondering if anybody could offer me some advice.
i have a pretty old computer and i was wondering if it is worth upgrading or just buying a whole new one. if i was to upgrade i would only probably spend under 200 bucks on it. i was thinking maybe just buying a better graphics card. would that help you think?

thanks

yeah just get a new graphics card if you had a duel core processor i would of said buy a whole new system