Hi djrecycle - firstly, can you confirm your computer specs for me again? So are you running 1GB RAM? And what is your processor power (you'll be able to find this in the "about this mac" section of the Apple menu).
Secondly, try downloading thr latest version of ITCH 1.0.4 here:
www.serato.com
Have you tried powering the unit using all the different usb ports on your computer? Are you using any USB hubs? The VCI-300 draws a lot of power on startup and needs to be using the most powerful port on your computer.
If you're still encountering problems, you could try this: before plugging the VCI in, switch the pc/thru switch to thru. Then plug the VCI into your computer and once the power light is on, switch it to pc.
Please let me know how you get on. Thanks