Start Cotchery over Curtis.
I'd go with Bush over Lynch. I just don't see much upside with Lynch this week.
You don't have much choice but to play McNabb. I think he is off to a little bit of a slow start. He is still not 100% after the knee injury last year, and he may not be fully 100% all season. But he is still way, way better than Derek Anderson. See how he does next week against the Giants. But after that he has a bye, so you better be thinking about a backup for week 5. Derek Anderson will be at NE in week 5, so that is not a very good option. JP Losman might be a decent option for week 5 if he is available. So would either Pennington or Clemens (whichever is playing) if available.
If you have been winning despite the slow starts by LT and Bush, be happy. They will come around. This week won't be easy for either of them as the defenses they are facing have been pretty good against the run in the first 2 weeks.