The technologies we use for shared hosting service and virtual private servers.
For shared hosting service, we use CloudLinux operating system, which is based on RedHat Enterprise Linux 5.
With our software, we offer our shared hosting clients guaranteed allocated resources. Using webhosting service from Powerhosting, you will be confident that you will have enough resources for your website.
The key advantage of CloudLinux operating system is that users have limits on the resources their websites use which ensures their website don't "hinder" any other web-sites hosted on the same server.
OpenVz vs Xen
For virtual private servers we use Xen 4 technology. It differs significantly from openVZ by the fact that you have practically a real dedicated server at your disposal, with the ability to add more RAM or disk space when needed.
Using Xen based VPS you can use virtually any function of iptables, and even install any operating system you choose.
Virtual private servers based on Xen in some situations are even better than a dedicated server. Particularily, you can easily move your virtual server across hosting servers in different countries, add RAM or launch your server from a backup in minutes, make backups of the whole server, which is quite hard to do on a regular dedicated server.