Hell, it looks like a 4 team league roster. Very solid.
You def want to pick up a WR for that last spot. Miles is an injury Magnet and what happens to Thomas once Caleb Hanie or whatever rookie the Broncos picked up in the draft are throwing to him?
Nelson and Marshall are great Pick ups and Jackson could produce. But still, need one more option.
And it shouldn't be any of the ones you've listed.
Instead, Look for the long shots...Hell, I just picked up Plaxico in one league
Or look for the starters on bad pass first teams.