speed keeps going up and down all the time.

[ryanchallis@iol.ie]

Every single torrent i try to download starts off very slow then maybe speeds up to about 300kb/s for a few seconds then drops down to about 80kb/s, then goes up and down again varying speeds each time...i have tried all the steps in the speed problems thread and nothing is helping...i should note that this is happening to my other computers and it happens when using both wired and wireless connections.I am not aware of any throttling by my ISP(UPC Ireland) on their 20mb package. I am really stumped about this. If somebody out there could help i would greatly appreciate it My router is a Cisco EPC2425 cable router.

Also i have provided a screenshot showing the speed changes.....

(Also it appears that my username is my email address could i get that changed?)