Open source client - Pelco Milestone

Hello. We currently have some Pelco DX DVRs and I'm looking to migrate towards IP cameras over time.

1. Is there an open source video client that will allow me to view Pelco DX series DVRs and an other brand NVR (Milestone/Openeye/Axis)?

2. What is a good industrial grade brand of NVR that is compatible with Axis cameras and has two NIC ports?

Thanks!