Also depends on the distance you will be shooting.
www.eastonarchery.com is also a good site, it will give you a chart to select arrow weight. You don't want to go too light, because then you will lack kinetic energy and penetration. I shoot 55# @ 27" and use a 2117 tipped with 100 grain heads...a lot of people told me this set-up was way too heavy and stiff for my set-up, butI cangroup the arrows within 1-2" @ 20 yards, and at 30 yds they are about 1/2" lower using my 20 yd. sight pin. I think the heavier arrows may cause issues (such as loss of speed)if you are shooting much over 30-40 yds. but that's a heck of a shot with a bow anyways. If you are staying under 30 yards I would recommend going with a littleheavier arrow.