If you search this forum (or any other forum for that matter) you will find endless agruments about the negative impact of link exchanges.
High quality inbound links from other RELATED websites will give you a boost.
If you have a link from a shoe shop to a site selling tapwashers then the search engine will discount the link. If you have lots of unrelated links it will treat the site as a link farm and penalise you. Read the webmasters guidlines on all the search engines and the will tell you the same.
__________________ Effective Web Design - It's not that difficult if you follow the rules.