capture video on intel 915+gma900

Just got a new comp, put my Firewire card in. computer recognize my camera, but when capture, I get unstable picture, sort of trembling.
Same card in the old computer was fine.
new is: P4 3Ghz lga775, Intel 915gav avalon motherboard, 1Gb ram (XP sp1).
old was: p4 1.5Ghz, Intel 845wn matherboard, ATI Radeon, ram 512mb (XP sp1)
Have the latest display drivers.
any experience with the problem?
Thanks