I agree with Jeri. A relatively modern PC (say, at least a 486 100 MHz), is hundreds of times faster than the fastest transmission over a 56k modem, the phone or cable line, your Internet service and the rest of the net.
Sure your PC is 99% of its time waiting for something coming through the cable. The solutions are:
1) Get your phone line checked by a specialist. It could be somehow damaged and introducing noise.
2) Try at night, not at peak hours
3) Try another internet provider. In general, this is the most probable source of problem. In my customer's experience, there is a relation between low cost and long waits.
Yours, Andrés Magré (as a singer, a good programmer)