Hi Tankboy,
If you are bringing m2vs etc into DVDSP then it does no further encoding and just multiplexes the files.
As to the softer/jaggier look, this could be either a scaling issue, or to do with field dominance, or both.
Check that the field order coming out of your media100 matches the settings in compressor and the desired output for (NTSC?) DVD.
Also check the output frame size is correct especially the vertical height. I believe there is a problem with 480 versus 486 height – the scaling producing issues.
It could be something else entirely, but there are two things to look at initially.
HTH
K