Internet massive slowing/ping spikes

[caltraskoo]

So I got Verizon FIOS 15 mb/s and its really nice. However, once my brother came home and started torrenting all this crap onto the computer, my laptop and computer sometimes streams much slower than usual (at like 20 kb/s instead of like 1.7 mb/s) and when I play counterstrike my ping rises from 50 (normal) to as high as 300 or so and it constantly at 120 or whatnot and it is annoying as ****. Are there are programs that I can use to detect the orgin of the process that may be doing this? I see no torrents running on the computer and is there a way to see who is connected to my internet?

Generally I am asking:
Why is this happening?
How to fix?

 

[office politics]

tracert will show where the slowness starts in its path through the inet

How to Use TRACERT to Troubleshoot TCP/IP Problems in Windows

most soho routers show connected devices and allow you to lockdown the network so only known machines can connect. lookup Mac filtering