Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
what hard drive is the footage located on? are you using iMovie, FCE, or FCP?

2gb shouldn't be terrible for playing back HDV. I highly doubt that's the issue (unless you are running a lot of other programs at the same time).
 
is the drive connected with USB? 'cuz that's a giant No-No and one of the most common causes of dropping frames. also, how much room is left on the drive?

only connect the drive with FW and make sure there's plenty of room (at least 15-20% free at all times).
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.