I think a lot depends on the portfolio, but I would ask to see a whole shoot-- as in, what he gave to the clients. It's easy for someone to pick out a couple of good shots from a mass of crap to make a nice or decent portfolio. There is nothing wrong *per se* with someone using a D40 but it says that they are not particularly invested photography, or that they are a beginner who has not made a lot of money in the field to be able to upgrade their equipment. But on the other hand, they may simply have found that the D40 works for them, and have stuck with what works.