If you host your websites on a shared hosting you are sharing the server resources with all the other people on the same server. If you purchase a VPS you will receive a separate server with its own operating system, central processing unit(CPU) and memory dedicated for you to use. The Virtual Private Server will also provide you with root server access which means that you will be able to implement changes on its configuration according to the needs to the applications you wish to host.
You can check the VPS packages offered by us here:http://www.freehostia.com/virtual-private-servers/
If you have any other questions do not hesitate to ask.