Four-year old KnowledgeNet racked up $17.5 million in its fifth round of funding, which was led by General Motors Investment Management. The depth of KnowledgeNet's courseware library with 15,000 titles, the strength of its management team, and customers such as McDonald's and the U.S. Postal Service make the company an attractive investment option, GM Investment says.

This is GM Investment's first venture into the E-learning market. KnowledgeNet, which has approximately $80 million in total funding, says it had 70% revenue growth in the first quarter compared with the same quarter a year ago and has achieved revenue growth for 11 consecutive quarters.

That's not a bad showing in a market where companies are struggling to make a profit. E-learning vendor SmartForce called off a proposed acquisition of Centra Software earlier this year because both companies reported weak earnings. Yet some startup E-learning companies are winning over investors. Last month, 3-year-old OutStart raised $11 million in cash in a second round of funding led by General Catalyst Partners.

KnowledgeNet says it will use the new money to hire staff and invest in developing more courseware and its learning-management system.