Kevin,
David is talking about simply changing the compression settings of your sequence, which, while forcing a render, can result in improved graphics and transitions etc. from a DV sequence to say, an 8bit one.
Note that if you are monitoring via FireWire, you will not get real-time playback anymore, but you can still spot check your timeline after rendering.
Best advice when working on a FireWire-based system is to wait till you’re sure your done to do this, and if it’s not obvious, this will not help if you are going to tape, only good for Web, DVD and similar delivery, as you can’t play uncompressed to tape via FireWire.
Have a wonderful day.