no need to worry - you aren't being attacked. Like Paul says, it is just a bit of a problem with your own network.
Those IP addresses are internal ones for your ethernet cards inside your pcs. It's when you start getting weird messages from your firewall along the lines of:
INCOMING ALERT
xx.xx.xx.xx is trying to connect to <random name>.exe via port xxxxx
that you need to be concerned. Then what you do is slap your son for looking at dodgy sites and letting the naughty spyware programs get on your network.
