Imagine, there two Thomas Scotts, both coming to America in 1634, both having children named: Elizabeth, Mary, Sarah and Thomas! And they both lived for a time in Cambridge, MA. A merge and corrections were made, and just as quickly I uploaded it into my RootsWeb, and nobody ever knew of my error!
One of the more popular sources for doing early New England research are a series of books called, The Great Migration : Immigrants to New England. The first series comes in three volumes with the title, The Great Migration Begins : Immigrants to New England, 1620-1633, published in 1995 and contains more than nine hundred sketches. The second series, The Great Migration : Immigrants to New England, 1634-1635, consists of seven volumes, the last volume published recently. Robert Charles Anderson, of the New England Historic Genealogical Society is the main author, and NEHGS is the publisher.
What can you do, if you can't purchase a volume? There are two options, the first is to go to www.worldcat.org (well-known library catalogue) and you should see that 320 libraries own a copy of the first series (1620-1633). Perhaps a library is near you.
The second option is to use Ancestry.com, if you are a subscriber. The first series is on their site, so in a way, it is free for you, since you already subscribe.