ACT! by Sage enables individuals and teams to instantly access key contact and customer information, manage and prioritize activities, track all contact-related communications, and grow productive business relationships.  For nearly 20 years ACT! has been the world's leading contact and customer relationship management solution for business of all sizes.

If you need to run ACT! on more than one computer and you are running a LAN (local area network), then ideally you need to share the ACT! database so you don't end up with 2 different data sources.

Sharing the ACT! database is possible, please use the link below for an excellent indepth explanation and step-by-step guide to be able to achieve this:-

How to Share an ACT! Database on a Local Area Network (LAN)