It all depends on the companies place in the tree, i.e. large corps in sky scrapers to small business run out of a garage. The larger companies will more likely hire a full time IT person for jobs such as Networking, and are likely to pay a lucrative contract to an individual for a programming position. Where as a small business would call a computer geek company to come out and fix what ever problem they are having for 70-120 dollars an hour rather than go overboard with a full time computer professional that would cost on the order of 50k to start for someone who knows what they are doing.
It all just comes down to money and need.