Active Directory with Failover Clusters?

We are getting 2 new servers with Windows Server 2008 R2 making us 3 servers total with one running Ubuntu server. We wanted to run failover clustering between the two new servers to keep our inventory program up but also want to run Active Directory on one of the machines with the AD backup on either the Ubuntu or the 2nd server. Is this possible? Any recommendations? We want to stick with 3 servers but want the redundantcy