ACM
Educational and scientific computing society, delivering resources that advance computing as a science and a profession. Also provides the computing field's premier digital library and serves its members and the computing profession with leading-edge publications, conferences, and career resources.
http://www.acm.org/

Personal Computer Association
Find advice for buyers as well as a list of PCA recommended computer retailers, the Code of Practice, complaint forms and more.
http://www.pcassociation.org/