>Perhaps I should render to an uncompressed AVI file?
Well, you better... DV AVI is evil. Unless you really cannot avoid DV, always render to some uncompressed or only mildly compressed format. Premiere and otehr editing suites handle the conversion to DV/HDV way better than you ever could hope to achieve in AE. Also make sure you adjusted your levels correctly. A lot of DV "blurriness" is simply caused by illegal colors which crap out the transcoder.