Conclusion
Depending on where you live, you might be able to get both cable modem and DSL Internet service for your PC. But coverage is spotty. The first thing to do is find out whether your house is covered.
Don't be surprised if you can get only one type of service where you live right now. In both cases, the phone companies have to install a lot of very expensive equipment before the service is available for you. If you live in any kind of a metro area, they'll get to you. Even if you don't, the chances are good that they'll still get to you.
Phone companies clearly understand that whoever gets to you first has a huge advantage over the other one, so they're all racing to complete their installations before they lose the market. They're playing for much more than just your Internet account. For example, AT&T recently bought a big cable company called Media One at a price that calculated out at over $5,000 per cable account.
NOTE
Did you know your business was worth $5,000?
One big reason they were willing to pay that kind of money is that they have a long-range plan to offer local telephone service through your cable connection as well. Yes, that's right. AT&T would have genuine competition for your local, not just long-distance, telephone business.
Have confidence. Corporate greed is on your side.