Tobias, this is a bit out off topic for this thread, but I am curious why have you chosen to use ESXi free and whether you have also considered Hyper-V R2
or XEN Server
which are both completely free and beat ESXi free feature-wise hands down (they even include HA and Live Migration for free).
If they would provide free HA and a working "hot backup" solution we would probably go for Xen. Xen is cheaper than vmware, ~2500usd per server for essentials (this includes HA, ...) so thats probably another longterm argument why we should go Xen.
Im not sure i like the "primary pool server" solution they have, if the primary server goes down you will have to "manually" tell one of the slave servers to take over the primary responsibility. This makes Xen Center unable to connect. I dont know how this compares to vmware's server center?
Live migration is included and works well.
Xen version 5.5 seems promising, adding support for snapshots in Xen Center, enabeling hot backups. But the release data is 17june i think.
Is veeam considering supporting Xen Server?
Anyhow, what we currently need is a working, free->cheap Hypervisor solution with working backups. And as already pointed out, veeam seems like a good solution, and it would be perfect if the price would be adjusted to fit the ESXi price tag.