I'm sure there are plenty of threads on here about this, but I'm just now catching up on it. I got the netflix through my xbox 360 and they have all the heroes epidodes up. It took me a week and a half to watch all of them up until where the series stands now. That's 47 epidodes in 11 days. This show has renewed my faith in network television. Fucking amazing.
If you have a gold membership and a netflix unlimited account it's "free." I pay $9 a month for netflix. There's a decent amount of movies too you can stream. Mostly stuff that's been around a while. All in all I'm happy. All of heroes, all of the Office episodes...heck yeah.
Just an FYI, you can watch most shows online for free at the the site from the show (like nbc.com for Heroes or abc.com for Lost). If you can get past 30 second commercials you can save the money. I'm a poor college student so I rather just deal with short ads lol.