Okay, I think I know where you are coming from.
From the sounds of it, you are currently using antenna (off the air) and need to upgrade because all of the signals are going digital in metropolitan areas in September.
So to explain things a bit, your old tube TV currently has an analog tuner. What you really need is a digital tuner to receive the new signals. These are all included in the new TV sets, most of which support HD anyway. But all you really need is a new tuner. So, you could get away with simply buying the tuner ($50-100) or you could get a whole new TV set.
Regarding the audio, "Televisions" have built-in speakers for sound. "Monitors" (typically) do not. If you stick with TVs, you will get both the digital tuner and speakers for basic audio.
Assuming you want to get a new TV, almost anything will do as most sets are really really good now. Personally, I think Bravia (and Sony) are overpriced. You can get what you need for a lot less. It doesn't sound like you are too picky or tech savvy so I wouldn't worry too much about LCD vs Plasma. For the record, plasma has better blacks, but the differences are slight.
My best advice would be to look at the weekly Future Shop flyer and see what is on sale. Go into the store and look at the set before you buy it. You can ask a salesperson for the best 'bang for your buck'. Oftentimes after you get to a certain price point, you are paying more and more for less and less features. However, you don't want to just buy the cheapest model because sometimes upgrading $10 can mean a lot more features.
The good news is that once you have your new TV, you can simply connect it to your old antenna (check to make sure it has a co-ax connection) and away you go.
The 'bad' news is that because the signals are digital, you may or may not get some of the old signals you used to get.
These signals are digital now. You won't get channels 'half-way'. You either get them with a near-perfect image, or you don't. It may be annoying that some channels you might have received with a snowy picture you won't receive at all anymore. But if you have an outdoor antenna, you should have the best setup possible for over-the-air (OTA) and best of all -- the signals are free!
I wouldn't recommend looking for a Wi-Fi TV as it is likely one of the higher end models and you will be paying a lot for other features that you don't need. If you want to watch streaming video from the Internet, check your TV to see if it has a computer monitor connection or other connections to that you can connect your computer to it. Then you can switch between watching TV OTA, or using it as a monitor for your PC.
There are a lot of retailers that have what you need. Shop around.
