yea.. go on each companies website.
and look for "coverage" or coverage map or something,and check your area.
cause i know where i live, NO ONE has tmobile cause they dont have towers around here, but where my friend lives in another state, EVERYONE has tmobile. so just check it out
also, when you chose a company, wen ur ready to pick a cell phone go to reviews.cnet.com
they have the best user and editor cell phone reviews =]