>Also since the usb trackball supports 3 mouse buttons can i just use those for the trackball and spinner and not connect any of the buttons to the IPAC? Will i be able to use the mouse buttons as fire buttons when needed?
I think you can (I never used that specific hardware), the only problem is if you are not using the mouse (unplugged), then 3 buttons will be dead. This shouldn't be a problem, but I don't know your exact situation and what you are trying to do.
>What video card do i need.
Well, yes, pretty much anything ATI. Unless you are running fairly new games you will not need to really worry about how many MB. The only thing to be sure about is whether or not your computer supports AGP cards or just PSI. AGP are dirt cheap (search Ebay or Froogle.com), but many older computers do not support it.