I have a 17 PowerBook G4 purchased from the UK in August 2004. I'm thinking of purchasing a 30" Apple Cinema Display to attach to the PowerBook. However according to the ACD specs, I must have a dual link DVI port to be able to handle the output. I do remember upgrading the graphics card so that I had the 128MB of VRAM instead of the standard 64MB. How can I determine if I have a single or dual-link DVI port.? Thanks in advance.