Technology has changed quite a lot these days and going for a cable modem ISP makes no sense. DSL is definitely a better bet. Most of the big players give you an ADSL (Asynchronous Digital Subscriber Line). They first install a telephone line and then connect this line to an ADSL Modem. You can connect the ADSL modem to your PC either through an ethernet cable or a USB Cable, depending on the make and model of the modem. Cable modem connections are prone to frequent failures because of the careless attitude of small-time service providers who run their business only for money without the knowledge of what customer service means. I have seen cable internet providers in several cities and all of them suck big-time.
There are two providers who give you reliable ADSL connections. Airtel and BSNL. BSNL gives connections more readily than Airtel does. Airtel is still developing its infrastructure.
The bad ADSL providers are Sify and Tata Indicom. If you subscribe to their services you have to depend completely on luck.
If you don’t want to go for ADSL, you can choose BSNL or Tata Indicom Dial-Up. Dial-Up is more reliable than Cable Internet though it is slow. But for people who do not use the internet much, Dial-Up is a good option.