Basically, in the x86 world, and Oracle Enterprise, your license multiplier is x0.5 (x0.75 for SPARC).
So, you have a couple of 2-socket, quad-core, DL380's.
The standard answer is: Per HP box, that will require FOUR Orcl enterprise licenses. (8 cores * 0.5 * 1xORCL)
Now, where it gets tricky is with the HA/DRS stuff, and multiple ESX/vSphere hosts in clusters. In traditional environments, a lot of people do not license standby machines, as they are simply there for hardware redundancy so that you can MANUALLY fail over to that should your production box go kaput. Oracle does not require you to license this.
The other option is, you can set up RAC to cluster the two machines, but THEN, Oracle requires you to license BOTH boxes, or (16 * 0.5 * 1xORCL), due to the fact that you'd be sharing load between both boxes live or automatically (i.e. clustered, or automatic-failover-scenarios/active-passive, etc)
Now, let's relate that to how ESX hosts work in clusters. Your Solaris/Linux/Windows "VM" that is running Oracle is essentially the equivalent of ONE of your physical boxes. But you don't have two, right? Well, this is the grey area. At any given time, you could lose an ESX host, or DRS could vMotion that VM over to the other host with little to no downtime, all done automatically. Even if you have multiple VM's with anti-affinity rules in place, there's still a likelihood that at any given time, that VM could live on either of those two hosts, which makes it a live box, not a standby for hardware redundancy.
So, what you have to come to terms with, is that your VM running Oracle will NEVER EXIST ON MORE THAN ONE HOST AT A TIME. Oracle reps/sales will fight you to the teeth on this, but even Gartner has questioned their tactics on this. You're going to get a lot of pushback. Be prepared for it.
I've been fighting this same battle for over a year now, and just recently claimed victory, convincing my superiors this was the right way to go.
Go virtual, or go home.
