Academic types used to make a big deal about what type of top-level domain name you had. .net was for the technological elite. .edu was for education. .org was for clubs and non-profits. .com was for those dirty money-grubbers.
The difference has largely become meaningless, though. As long as you have one of the major top-level names, and not one of those johnny-come-lately's like .biz or .info.
The cost associated with reprinting all of your material is probably significantly higher than whatever aesthetic, theoretical (or theological) difference there is between .com and .org.
And if you can get both .com and .org, do so. Redirecting from one to the other is simple.