This is often a question that many people ask. OpenVZ tends to be priced cheaper. But that's because OpenVZ servers can be oversold and you may not be actually "buying" resources. You're just paying for something that's already been sold. This is why I would suggest Xen servers, which can't be oversold very easily. But they do cost more. Also note, there's something called Xen PV now. I wouldn't suggest it much, because it defeats the purpose, as it can be oversold.