Your problem could be down to an oversubscribed ubr though usualy your ping times get bad when this is the case. Is there any way you can connect the games machine to the net directly to check that the ics machine is not the problem.
You could also check for packet loss by going to
http://www.dslreports.com/tweaks
This is supposed to be for tweak testing but it does give you a packet loss chart.
HTH
Welcome to the forum BTW