Watching TV on the internet is something I do daily.
I don't even own a TV anymore, and I used to own three!
The biggest difference between cable TV and internet for me is, I don't have to worry about missing shows, TiVo or any of that other stuff.
So what are the best places to watch free television online?
Well I can't tell you what is statistically the best, but I can tell you what I use and what works for me.

This is my clearing house for TV through the internet
Here I can find out what came on, and where I can see it.
They have a list, that shows all the new TV shows posted and where you can watch them.
Most of their links are good, and they do a really good job of eliminating dead links daily.
Actually, I haven't run across a dead link in awhile.
But like I said, here I can see if NCIS came on last night, and where I can see it.
(I love me some NCIS)
And yes the problem with internet TV is that you watch the show the day AFTER it's broadcast. But you get used to that.
And usually the links to your shows STAY online for months or even years.
So if I miss The Big Bang Theory Monday, I can watch it Sunday.
Oh, did I mention it's FREE?
And Great Stuff TV also lists BBC and syndicated shows (like Dr.Who and Legend of The Seeker).

My next best site for TV on my PC.
I don't rely on TV Shack for new shows, but they have a vast array of old shows.
Well not really old.
But for example I recently caught an episode of Gary Unmarried and wanted to go back and see the series from the start.
I looked up the links and there it was.
Since a sitcom without commercials is usually only 20 minutes long, you can watch a whole season in no time at all.

The only thing I have against SideReel is that their main menu takes so long to scroll down.
They haven't gotten that A-Z category thing down yet.
But they do have a ton of shows.
If not for Great Stuff TV and SideReel, I would have missed a lot of really good British programing.

A little more trouble (you have to launch their applet) and kinda quirky, but Ninja Video allowed me to watch the entire run of Buffy The Vampire Slayer and Angel over the course of a few months.
And now I'm catching up on Supernatural.
I love their DivX links too, really good quality.
But like I said, the site can be quirky and you may have to load, re-load, clear your cache, sacrifice a virgin (okay...not really) and swear a lot before you get a video to load.

I love their TV spots (the Alec Baldwin Superbowl spot was priceless) and they are really good for current shows.
As long as they aren't CBS shows.
And you can watch really old TV shows here as well.
I watched the entire run of the Addams Family beginning to end with no problems and in really good quality.
I also got to see most of The Pretender, but I did have to look elsewhere for some episodes.
Hulu also has movies and some Webisodes.
And they do have commercials, but hey, I can handle a thirty second commercial break better than I can what is it up to now...like three minutes on network TV?

My last resort.
Their lovely 73 minute daily time limit seems to kick in whenever they want it to, be it 73 minutes or 20 minutes.
Quality can be really bad, and they have a bad habit of getting their video sound so off-sync at times, you think you are watching a 1960s Godzilla movie dubbed in English.
You can get a paid membership there, but why would I pay if I get all those great technical problems?

Now there are a few I use occasionally.
For instance I watched Corner Gas and Ultraviolet (the British TV show, not the movie) on YouTube.
Usually the quality is not really good, but if you want to see it bad enough, you'll handle it.
The ABC, CBS and NBC networks all have their own sites, but the videos are usually here today, gone tomorrow type things.
And I HATE The ABC network video player, that's why I was so glad when they hooked up with Hulu.

Yes a lot of these sites get taken down, and with the exception of Hulu, they are not sanctioned by the networks.
And I keep hearing rumors that Hulu and YouTube may go to at least partial pay sites.
As far as Hulu goes, News Corp. Deputy Chairman Chase Carey said yes, they would go to a pay site, but then News Corp. itself said no.
Maybe Carey jumped the gun and scared everyone.
With Net Neutrality hanging over our collective heads like the Sword of Damocles, who knows what will happen?
In a few years (or months) we may not be able to watch TV over the internet like we can now.