Need help with upgradeing my comp

Recently i made the decision to upg my comp. I want to change my video card with a PCI one and so i need to also change my mainbord and my cpu.
Know im asking anyone whos willing to help cause primarly i wanted to by
a x700pro from saphire
CPU AMD ATHLON 64 3000+, SOCKET 939, FSB 2000 MHz
(don`t know what mainboard yet).
But know what to do some people said that i should wait for mainboards wit ddrIII someother said that x700 had probs with the rams.
Any sugestions are welcome

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