awesome speed on wireless very slow on LAN

So Im downloading torrents at 100kbps (on my desktop PC that is connected to the wireless router via ethernet cable) for the last 4 days, and then this morning I realize my download speed will not go above 11kbps. Its not just downloading, but any other sort of browsing I do, it just wont go more than 5-6kbps (only on my desktop. Wireless connections via laptop are still giving good speeds around 140kpbs).

Did I fry something on my wireless router?

My wireless laptops that are connected to the same router are giving me perfect speeds, around 140kps. So it is not the ISP that is giving problems. I even unhooked the router, and connected my PC directly to the ethernet cable from the ISP (bypassing the router) and the speed resumes to 140kpbs. It is only when I connect my PC from the router that the speed drops.

Any ideas what the problem may be? And how can I resolve it?

I have a GigaFast WF719-CAPR wireless router - yes the really cheap ones.
Since I have tried upgrading the firmware but to no avail.

Any help/advice would be appreciated.

Thanks in advance.