...CPU or Graphics Card

..... have got enough dosh for one or the other ..... which do I need the most?, .... better graphics card or faster cpu? ..... an fx5600 256mb or an amd athalon xp 2800+ ? .... to improve the specs I currently run (as below) ..... my motherboard will take that cpu, I've checked ..... just looking for advice/ ideas ..... cheers ;)