Quest Software (QSFT) has announced that it's agreed to be acquired by two private equity funds, Insight Venture Partners and Vector Capital. Aliso, Calif.-based Quest's acceptance follows an increase in the buyout offer by the private equity group from $23 per share to $25.75 per share, or about $2.17 billion in cash. Quest also agreed to the inclusion of Vector Capital in the buyout group. Reports said Insight's successful offer topped a