I agree with Paul and the others. No matter the weight of your pack and the rest of the equipment, Trekking Poles can make quite a difference in your comfort level and the affects on your knees.
I am sure that Paul will particularly agree about the problems of terrain particularly here in the east which can include a lot of rocks, tree roots, etc. And depending upon where you hike as an example in the Adirondaks, and I would presume the White and Green Mountains, you may have such things as ladders, and other nice obstacles.
The trekking poles will not only take a lot of stress off your knees both climbing and decending, but will also contribute substantially to improve and maintain balance.
If you can deal with some of the new offerings you can purchase some very light poles. In particular if you can deal with a non adustable length pole, you can get something such as the new $95.95 (including shipping) Gossamer Gear Carbon Fiber Lightrek Plus poles http://www.gossamergear.com/cgi-bin/gossamergear/Lightrek-Trekking-Poles.html
Paul can comment on the Gossamer Gear poles. If you want more expensive non adjustable poles they are available here on BPL and there are many adjustable poles available as well.
You can read the reviews of trekking poles here on BPL at http://www.backpackinglight.com/cgi-bin/backpackinglight/trekking_poles_review_summary_and_gear_guide.html