If you mean capturing DV (from lets say a DV camera) then all you're doing is copying the data over in real time.
But the codec itself is lossy. If you are capturing analog, you're just capturing analog and digitizing it to a lossy codec. Unlike capturing DV, you're compressing the analog signal.
MPEG2 can have a much higher bitrate than DV. MPEG2 is a long gop codec, harder to edit. DV is not. Each frame is a frame on its own. Both are old tech.
I recommended going with the capture device I linked because DV is very easy to edit and tools like iMovie (which most Apple users have by default) handle it very well. You can also backup to a mini DV tape for archiving. In this case you don't lose quality since you're going from DV to DV.
If you go from lets say your captured DV files (via analog connection) to DVD (Which uses MPEG2) you will lose quality, but its not noticable.
If you edit MPEG2 then go to MPEG2, you will lose more quality because usually consumer MPEG2 products use very low bitrates.
So my recommendation for the DV product still stands. It's universal and the device is portable for converting your old videos to DVD after capturing. Editing it in iMovie to clean it up a bit is also another nice one.
Hope this helps