file transfer between xp and 7

i have 4 pcs at home 2 with 7 one with vista and i have a old p4 with xp32 bit. it wont handle 7 or vista the core spikes at like 60-80% at idel for like 5 misn then drops for 2 and does it again. i just want to know if there is anyway to transfer files from my win7 pc to the xp pc over the enthernet port? because my dl is capped and i dont want to dl something 2 times. AND external hhd are 2 slow and the pc is just 2 far away.