Judging by the huge number of questions on this site about the music on ads, and the various other web sites dedicated soley to the subject, I would say it does. the comanies used to make up their own litle jingles (remember Shake and Vac, or R Whites, or That's the wonder of Woolworths) but these days it's about getting the coolest track in the background (although there are a few companies sticking to the old formula, like Currys and Asda). I guess Levis started it off in a big way with I Heard It Through The Grapevine - back then it was innovative, but I still think it makes a difference if there is a good tune.