SAN FRANCISCO (AdAge.com) -- PC marketer Gateway is working on a project basis with Southern California startup Siltanen/Keehn, El Segundo, to promote Microsoft's Windows XP operating system.

But Gateway has an ad campaign of its own, which will pit Profile 4 against iMac in head-to-head comparisons--a rarity in the computer industry. Both companies target their all-in-one computers to ...