The computer doesn't have to be a high-end monstrosity either. Personally, I use a Mac mini.
Watch on the go
Streaming video isn't just for TVs and computers, however. Maybe you want to watch video on the go with a tablet or smartphone. Because online services are Web-based, it's no problem, as long as you have a decent Internet connection.
Certain services work best with certain types of mobile gadgets. For example, Amazon will stream video to almost any tablet, but it works best with Amazon's own Kindle Fire. However, it doesn't have a smartphone app, while Netflix does.
If you already have a mobile gadget, or are planning to purchase new ones, make sure they play nice with the services you use.
Mix and match
There's no rule that says you have to choose just one of the options above. You can stick with cable for now and gradually explore free streaming video services.
Ease your way into it and find out what works and doesn't work for you. Take advantage of the free trials that the major streaming services offer.
Don't forget that cable companies want to keep you as a customer. They're upgrading their services and trying new promotions to make their offerings more attractive.