Running a Small Business on the Linux Platform?

WinDOOR asks: "As part of a small-mid sized family business, finding a way to rid ourselves from the dependence of using Microsoft products is a very daunting challenge. I've been searching for a good Linux based ERP/CRM software that's adequate for use with about 20 or so users and that can handle light manufacturing and POS type order inputting. I've looked at Compiere, but consider the Oracle tax to be one and the same as the Microsoft tax. We don't have the money nor expertise to design our own solutions like the big corporations that have switched sides. What packages or vendors have you had the most success with? Is Postgre or MySQL an acceptable database backend? Is there a viable replacement for MS Access yet? What language would be best to learn if I had to create my own solution? Do CS Students do this kind of work to pay the bills?"