Question
I have a very large oak tree right next to my house Portland Oregon.  It really needs to be pruned.  If there is any sort of strong wind it drops pretty big branches. We had an estimate to get it pruned - about $600.  So this is something we would rather do ourselves if at all possible.

Answer
If the tree is large then pruning would be best left to a professional. Chain saws can be dangerous. I would try and use a Certified Arborist to prune the tree, They will do a better job. If you can not fine a Certified Arborist then ask fro references and go look at other pruning jobs the company has done. That way your tree will not turn out to be an ugly job.   
Here is a link to the web site of the agency that certifies Arborist and you can search for one in your area.

http://www.isa-arbor.com/findArborist/findarborist.aspx