SATX,
If you just want to look up the provider, go to
http://www.webmasterfree.com/iplookup.html and download the software for free. It doesn't give you specifics like the user's exact location, but it'll tell you which provider the person's using.
I know some software companies out there allow people to download free demo copies of their product and often some of these programs will pinpoint the person's exact city or at least state. I know
www.visualroute.com offers a demo version that'll track the person's location, but it's not always reliable. Those with firewalls like RoadRunner don't always work. Error msgs usually occur right before the complete trace is done, and depending on how far the trace went, it'll provide city and state.