I used to work for an ISP and when customers use to ask us that question, my boss would usually say,
"No way, Jose." It is possible for an ISP to set up a static IP to a user on dial-up (which I'm assuming you're using).
However, it isn't cost-effective to the ISP b/c they can't assign that IP addy to any other of the dial-up
customers during the times that you're logged on. Well, I guess you can but there'll be problems if you
dial-up and the IP is already used.
IF you really want a static IP, you might want to check a broadband technology. Usually those offer a static
IP with the service.