Apple IS a trademark of Apple computers; however, it only pertains to the catagory of computers. There is also a trademark of Apple for Apple Records (the Beatles old record company) in the catagory of entertain industry. Windows, we all know about that...
Common words can be TMed depeding on thier usage. Therefore, just because you hvae a "apple" domain name does not means you are infringing. applepie.com would be ok since it deals with apple pies and pastry, it is a different industry. Neither company could prevail in suit against you (they can come after you, it doesn't mean they will wim).