Gettng links to your website has a very positive impact:
Getting the right links to your website is an activity that pays off time and again. When the links are permanent so are the benefits.
There are certain web directories that are worth paying to be listed in annually. Other than that the links that are worth pursuing are the ones in your own market sector.
Getting links from your suppliers, distributors, clients and partners is the first place to start, after that the search for links should centre on seeking out links from sites that have relevant content to your own.