Internet Search Engines

I have a client running windows XP Home edition.

Whenever he uses the search button top find something, www.overture.com pops up requesting further search information.

How can we get rid of this access to overture in the search engines or at least move it form first selected option?

I hesitate trying anything before asking, since my search capabilities were once taken over by Xupiter.

I looked in the registry, but could not find anything listed for overture or www.overture.com.

there are also no easily identifiable programs like Xupiter had.

any ideas?

thanks,

gilles mailhiot