unless u want to watch a movie and enjoy the view outside ur condo window at the same time..
A TV USB port can only read from USB sticks at this point, not from the portable exterior hard drives.
It supports Avi, Divx but also mkv files on late models. U can easily convert digital movies to mkv file with mkvextract and mkvmerge, both programs are free to download online.
To play movies from a portable hard drive u will need a "moviebox" ( Asus, Noontec, Play!on etc, 3000-5000B), or a laptop and feed to TV with HDMI cable.
Movie box has the advantage of 5.1 or 7.1 surround sound option if u hook it up to ur Hi Fi system. Late models of Blue-ray players and Home Theater System, Sony BDV-E380 (16000B) for example, also can play movies from portable hard drive via the front USB port, the old models can only handle USB sticks.
3D TV's and 3D blue-ray dish players are backward compatible. U can get regular pictures with regular feed. To get 3D effect u will need a 3D feed, from a 3D dish playing on a 3D player and the special glasses. I hate the whole idea, especially the glasses.
Get an at least 46" because wide screen Blue-ray format is getting more and more popular, in which u will lose top and bottom parts of the screen. My 42" looks smaller and smaller everyday..
I like to make use of product specs online. I like to look at the models at the shops, compare the specs online and then go back to buy.