As per my experience goes I don't think that two way link exchange is of any help because Google, Yahoo. MSN easily find those links and give no importance to them. And those links remain as useless. Rather one way link exchange is better. That gave rise to 3 way link exchange. That too if found given no importance.
I want to know one thing in how many article directories I can submit one article? Can I put the same article in Forums and blog. Will it be of any help? Or one particular article for particular is good?