Ping rates are the time it takes a packet of data to go to its destiantion and return back to its source.
Every router the packet traverses affects the overall time it takes to complete the trip.
Ping times will change based on many, many factors. Route changes on the Internet, and loads on the various routers the packet must traverse are the major items which will effect ping times.
Right now, route changes are happening quite a bit due to the hurricanes, which devastated the telecomm network in the southern U.S.
As ISP's who were directly impacted by these outages come back online, routes on the Internet will change. This can, and will, cause potentially drastic changes in many ping times to various destinations.
Also, priority to voice communications is much higher than data communications, so as the voice comms increase, there is less available bandwidth for data. Sprint, which operates the largest Internet backbone in the U.S., cuts is data bandwidth as voice communications increases, which will impact almost every user on the Internet.
Certainly, your computer can impact the ping times, but the impact is usually derived from how busy your local connection to your ISP is, or how busy your local LAN/WAN is.
If your direct connection to the Internet is flooded with requests, then it can take more time for your computer to respond to network requests.
Cable users will normally be more impacted by excess local network traffic than other types of broadband connections due to the sharing of the fixed bandwidth at the local node and will see a greater variation in ping times.
Hope that helps.
