You need 2 identical Proxmox VE servers with the following extra hardware:
Free network card (connected with a direct crossover cable)
Second raid volume (e.g. /dev/sdb)
Use a hardware raid controller with BBU to eliminate performance issues concerning internal metadata (see Florian´s blog).
My servers are both Dell R415s (2x 8 Core 3.0Ghz, 16GB RAM 1x 500GB SATA, 1x 16GB USB, 2x 10/100/1000 NICs) - is it better to install server software on the USB and then run DRDB volume on the drive OR partition the drive using the management utility and not use the USB memory?
I also dont have a dedicated network port - im assuming that this is very important? does it have to be 10/100/1000?