When you say it keeps dialing up, do you mean that it tries to connect when you are not present at your machine. It could be that the windows 98 machine is trying to gain access. On the XP machine right click on your dial up connection and select properties. Select advance and ensure that you have not got the box checked next to "Establish a dial up connection whenever a computer on my network attempts to gain access to the internet". This will stop the 98 machine from dialing out.