Hulu.com is great if you don't have cable, and I don't, and you need a quick fix of some of your fave TV programs.
They do not post every TV show. Some shows can only be watched on the website of the cable channel they are screened on through the TV (tnt.com for example). Unfortunately, a lot of popular shopws fall under this category (Dexter, The Closer, etc).
You also don't get every episode in the season shown online. For example, they always make about 11 episodes of Lie To Me available, but no more than that, so you have to get the season's DVDs through netflix afterwards.
They also do not leave them up on the hulu site interminable. House, M.D. episodes are available for about a week and then they are gone and replaced. Also, you can't always watch the episodes in order, this has happened to me with Grey's.
Having said all that, I love hulu.com and it is FREE! How many things in the US are free? It is paid for by advertising. Every 10.12 mins of your program, you are interrupted by an advert from the sponsor of the day. No biggie. Gives me a 10 second chance to leap up and grab a snack from the kitchen.
Also, for a variety of TV shows to watch through your computer, also check out fancast.com. They usually have CSI and other shows of interest.
Enjoy!
Clare