WHAT IS UNMETERED BANDWIDTH? With unmetered bandwidth we allocate a dedicated portion of a data line to your VPS and let you go, not calculating traffic flow.  That portion is available to you 24/7 regardless of how much traffic you take up in a month.  However, the size of the data pipe is only so big.  So, only so much can flow through it simultaneously.  Thus this is suited for sites which have a steady, low and even traffic flow.

WHAT IS METERED TRAFFIC? METERED traffic allows you a specific total amount of data flow over an entire month.  Althouigh this limits you, the quality of the traffic is much higher.  Data is sent out on a full 10/100MBPS date line so the pipe is very large.  This means if you have large spikes of bandwidth or file demand the VPS will be able to handle it without a problem.  This is best for sites which have peaks and valleys of visitor flow, or medium to large sites. 

IE, in the case of VPS-3 if you know you are going to be under 500 GIGS of traffic every month, choose the 500 GIG option.  The data pipe will be larger.