If you don't have enough money for both a television and a computer, it should be no competition -- get a computer. Not only can your Sim go job hunting, they can surf the Internet, play games or build on their budding writing career. It becomes slightly less important after a job has been found, but still quite useful.
Having a television does have its uses though. Unlike the computer, it's possible to exercise in front of the television. It's an excellent (and free) way to keep your Sims' health up.
source:mycheats.1up.com/view/section/3166827/26963/the_sims_3/pc