i dont know about the Dreamweaver but the the photoshop cs2 and illustator cs2 finely work on windows 7....
I woud say if you are upgrading anyway and you are comfortable with CS 2 then you have nothing to lose. If for some reason DW does not work then you can upgrade but if Illy works I would think DW would as well.
But you certainly have nothing to lose by trying before upgrading.
The upgrade is reasonable enough for one app.