The chainsaw threads here often have a lot of innacurate information (without getting into the details). Everyone has an opinion, but the useful facts often get discarded. One issue I will comment on is the suggestion for a top handle saw. Bad idea. Top handles are a specialty purpose saw and should be left to pros that need them for limbing while in a tree. Their balance and leverage make them less safe, especially for the novice user.
As for brands, Stihl and Husqvarna are the Chevy and Ford of chainsaws, but by no means the only good saws out there (and they both have good and bad models).
Arboristsite.com is one of your best bets for saw info.