i have a mac pro , canon xha1 and i capture all my footage using firewire input just like you are doing and im running Final Cut X.Now idid notice grainy video clips after or during capture/import, for some reason the video doesnt look great when previewing or editing but i can assure you that when you are done editing and render to dvd and play it on ur hd tv, you will be amazed by the clarity of your movie, im used to this process now. i would suggest a third party capture card and a good monitor,i switched to 2 24 dell ultra sharp monitors and they dont look so bad