Compaq Computer Corp. said Friday that it has awarded its estimated $300 million global advertising account to Foote, Cone & Belding Worldwide, New York, just as the computer company prepares to increase its overall ad spending by more than 25% in future quarters. The Houston-based computer giant selected FCB following a review that began early this year. Incumbent agency of record DDB, New York, participated in the review. A new campaign reflecting FCB's work is due to debut by October, Alan Hodel, Compaq senior worldwide manager of public relations, said. Compaq also officially named Hill & Knowlton, Houston, as its public relations agency of record. H&K had been serving on an interim basis for several months, following Compaq's decision to end its agency-of-record relationship with Shandwick International.