Ping skyrockets for no reason every 5-10 minutes.

During league of legends games, my ping goes to about 5000 and I lag like hell for about 2 minutes. When watching youtube, the video just pauses for a few seconds (>30) and then starts up again. It happens about 20 times a day and it's really annoying.
It happens regardless of whether people are on the network with me or not. I wirelessly use a 2wire 2701hgv-w on an x64 machine. Resource monitor is usually just like this: http://puu.sh/YxVq
But the only thing on firefox that I'm on is reddit and facebook. Any ideas?

You need to run more test,

you need to disconnect all computers and connect only your computer, install an application for internet bandwidth monitoring. I am sure you can find a dozen @ download.com. or use download limiter, it shows which process eats up the bandwidth. once you get the lag, check if your computer is uploading or downloading something.

Alternatively, it could be your ISP, or maybe you have purchase like me a DLINK router they are terrible.