It depends how much you are upgrading to.
it has no effect on internet speed
Yes Basically everything that has Internet but if you are not getting Internet you should try getting closer to the modem to see where the problem is!
1)the rainbow connection 2)electricution 3)a better modem
You would need a cable modem when you want to connect to a cable internet service.
The cable modem that you got from your service provider is adequate. You might get a little faster service with another modem but it will probably not make much of a difference.
Without the modem you can not connect to the internet.
Well it depends on whether the computer connects to the internet with this modem. If you're talking about an external cable modem, you would probably lose your internet connection. If you're talking about an internal dialup modem inside the computer, removing it would mean you can't connect via dialup but it would not affect the external modem. Hope this helps
Your internet can be not faster than your internet connection (DSL, cable modem and so on). If you have a slow internet connection, installing a new router will not fix the speed. It might improve stability of wireless signal and security though.
Yes a modem and an ISP (Internet Service Provider) are required for an internet connection. Depending on the type of internet the ISP will issue you a modem.
if it is a dialup modem there are some free dial up internet providers but for a cable/dsl modem this is not possible as you would need a isp to provision the modem on their network
Fix a modem? You would be better of buying or getting a new modem Depending on your needs they can be cheap or more expensive.
To connect to the internet you need to first buy an internet connection. You must then plug your internet cable into a modem. Finally you must have connection to the modem from your PC, most computers will automatically connect to the internet if the hardware is in place.