I have installed windows xp sp3. But I am facing problem with the Cable internet. In sp3 I am unable to surf the cable internet but dial up internet can be run. Help me

Works fine for me - I have cable too.

Are you connected to your cable modem by ethernet?

I have that problem too. I downgrade my Windows Vista due to my Notebook spec (RAM) to Window XP. Unfortunately it gave me a problem on the internet connection. The connection are damn slow. and sometime request time out. Any solution on that? Sorry i am newbie, how do we know we are connecting to our cable modem to ethernet? and which one is the good one?

If it is not wireless then your modem will be directly connected by a cable to a network card fitted in your PC, this (Rj-45) connection is usually found at the back of of the PC or to a router which in turn is connected directly to the PC.This is an ethernet connection .However,most laptops/notebooks are wireless in which case there will not be a "direct" connection via a cable to the PC -the connection is made through a wireless adapter.
As for which is the better-this depends on individual preferences and circumstances. Although a wireless connection can experience latency (lag).

not nececerially

some cable modems use usb which can be problematic, thats why im trying to figure out which he has

Yes, of course jbennet.
I must admit I forgot about that possibility.