I haven't seen any options in the Intel drivers that come with IBM machines. Google doesn't say anything usefull either. Even if it's possible I doubt you'll be happy with the result. If you want better performance get a new card if your system supports it. Most IBM's I've seen did have an AGP port.
I wish Intel was more like Microsoft, pumping a shitload of cash into the development of a new videochip and make high end cards. They used to have the i740 which wasn't all that bad.