see what comes back. I usually get in the range of 20-30ms during peak hours on my cable modem.
If that returns under 70ms, then you should be fine on that aspect.
Next ping <a gaming server> use the IP of one of the servers you're getting lag from. If this ping is bad, do tracert <ip>
tracert will give you the ping of every router between you and that IP. Using this feed back, you can see where the ping starts to increase.
Another possible issue is someone on your home network is eating up gobs of bandwidth and this is crapping out your pings. If this is the issue, the only way to fix it is to stop the offending machine or setup a priority list for your physical network port or set your router to prioritize your game.