A little correction (couldn't help it). DV is not uncompressed. PAL DV is YUV compressed with 4:2:0 sampling (NTSC DV is 4:1:1. Not 100% sure).
When you "capture" from a DV camcoder, you're actually just copying the stuff. No image processing done here and thus no loss in quality. If you use just straight cuts with no effects whatsoever and export it back to tape you're not loosing any quality either.
But as soon as you use just a simple color correction transition or effect, you're gonna have to re-compress that part. This is where the DV codec quality comes in. The default MS DV codec isn't the best available. For example Canopus and Mainconcept DV codecs are much better.
Here's more info: http://www.adamwilt.com/DV.html