Done correctly, no other medium can establish an identity the way TV can. Don't scrimp on your commercial, however. Don't think you've got to buy the top-rated programs or just the top station to have an impact. Running more commercials on lower-rated programs is the ideal way to establish your identity in the minds of your customers. Be sure to stick to a consistent theme and message if you run more than one version of your commercial.
Cable looks like television to the viewer, but for the local advertiser it's very different.
Local cable systems are relative newcomers to the advertising game. A good many local advertisers wouldn't be on the tube at all if it weren't for the relatively modest cost of cable advertising. Local cable is best at delivering the cachet of television, at a fraction of the cost of traditional TV advertising. However, there may be two or more cable systems in your market. And since cable audiences are so fragmented, you can't use cable instead of broadcast television if you're looking to cover the market or build an image quickly.