Replying to External HD: USB 2.0 or Firewire?

So I'm looking for an external hard drive for my Mac Book right now, as I've depleted the storage on the 120 GB HD it comes with. I've seen a huge range of prices and storage, all ranging from 500 GB - $349, to 1 TB - $169 at futureshop. I've always found though, that with the cheaper ones with more storage, it almost always has USB 2.0 instead of firewire.

Now I always though firewire would be faster and better suited my needs for video editing to photography etc. etc., but after seeing the ridiculously cheap price of the 1 TB HD I've come to wonder if I needed the extra speed? Does the speed outweigh the storage space? I mean is it really that much faster? What are the pros and cons of both?